Humidifier reservoir

ABSTRACT

A reservoir configured to retain a volume of liquid for use in an apparatus for humidifying a flow of pressurised air comprises a base portion and a lid portion. The reservoir may be configured to improve its level of thermal contact to the heater plate using the flow of pressurised air. The reservoir may be configured to improve thermal contact between the reservoir and the heater plate by pre-compression upon engagement of the reservoir with the humidifier. The reservoir may comprise a removable intermediate portion, which may include the inlet tube and/or the outlet tube, for improved access for cleaning. The reservoir may also be configured to prevent overfilling. Overfill prevention features in the reservoir may include defined flow egress paths and/or formation of air locks.

1 CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from Australian Provisional PatentApplication 2013900901, filed 15 Mar. 2013, Australian ProvisionalPatent Application 2013901965, filed 31 May 2013, Australian ProvisionalPatent Application 2013902601, filed 15 Jul. 2013, and AustralianProvisional Patent Application 2013904923, filed 17 Dec. 2013, theentire contents of each of these applications being incorporated hereinby reference.

2 BACKGROUND OF THE TECHNOLOGY

2.1 Field of the Technology

The present technology relates to one or more of the detection,diagnosis, treatment, prevention and amelioration of respiratory-relateddisorders. In particular, the present technology relates to medicaldevices or apparatus, and their use.

2.2 Description of the Related Art

Human Respiratory System

The respiratory system of the body facilitates gas exchange. The noseand mouth form the entrance to the airways of a patient.

The airways include a series of branching tubes, which become narrower,shorter and more numerous as they penetrate deeper into the lung. Theprime function of the lung is gas exchange, allowing oxygen to move fromthe air into the venous blood and carbon dioxide to move out. Thetrachea divides into right and left main bronchi, which further divideeventually into terminal bronchioles. The bronchi make up the conductingairways, and do not take part in gas exchange. Further divisions of theairways lead to the respiratory bronchioles, and eventually to thealveoli. The alleviated region of the lung is where the gas exchangetakes place, and is referred to as the respiratory zone. See West,Respiratory Physiology—the essentials.

A range of respiratory disorders exist.

Obstructive Sleep Apnea (OSA), a form of Sleep Disordered Breathing(SDB), is characterized by occlusion or obstruction of the upper airpassage during sleep. It results from a combination of an abnormallysmall upper airway and the normal loss of muscle tone in the region ofthe tongue, soft palate and posterior oropharyngeal wall during sleep.The condition causes the affected patient to stop breathing for periodstypically of 30 to 120 seconds duration, sometimes 200 to 300 times pernight. It often causes excessive daytime somnolence, and it may causecardiovascular disease and brain damage. The syndrome is a commondisorder, particularly in middle aged overweight males, although aperson affected may have no awareness of the problem. See U.S. Pat. No.4,944,310 (Sullivan).

Cheyne-Stokes Respiration (CSR) is a disorder of a patient's respiratorycontroller in which there are rhythmic alternating periods of waxing andwaning ventilation, causing repetitive de-oxygenation and re-oxygenationof the arterial blood. It is possible that CSR is harmful because of therepetitive hypoxia. In some patients CSR is associated with repetitivearousal from sleep, which causes severe sleep disruption, increasedsympathetic activity, and increased afterload. See U.S. Pat. No.6,532,959 (Berthon-Jones).

Obesity Hyperventilation Syndrome (OHS) is defined as the combination ofsevere obesity and awake chronic hypercapnia, in the absence of otherknown causes for hypoventilation. Symptoms include dyspnea, morningheadache and excessive daytime sleepiness.

Chronic Obstructive Pulmonary Disease (COPD) encompasses any of a groupof lower airway diseases that have certain characteristics in common.These include increased resistance to air movement, extended expiratoryphase of respiration, and loss of the normal elasticity of the lung.Examples of COPD are emphysema and chronic bronchitis. COPD is caused bychronic tobacco smoking (primary risk factor), occupational exposures,air pollution and genetic factors. Symptoms include: dyspnea onexertion, chronic cough and sputum production.

Neuromuscular Disease (NMD) is a broad term that encompasses manydiseases and ailments that impair the functioning of the muscles eitherdirectly via intrinsic muscle pathology, or indirectly via nervepathology. Some NMD patients are characterised by progressive muscularimpairment leading to loss of ambulation, being wheelchair-bound,swallowing difficulties, respiratory muscle weakness and, eventually,death from respiratory failure. Neuromuscular disorders can be dividedinto rapidly progressive and slowly progressive: (i) Rapidly progressivedisorders: Characterised by muscle impairment that worsens over monthsand results in death within a few years (e.g. Amyotrophic lateralsclerosis (ALS) and Duchenne muscular dystrophy (DMD) in teenagers);(ii) Variable or slowly progressive disorders: Characterised by muscleimpairment that worsens over years and only mildly reduces lifeexpectancy (e.g. Limb girdle, Facioscapulohumeral and Myotonic musculardystrophy). Symptoms of respiratory failure in NMD include: increasinggeneralised weakness, dysphagia, dyspnea on exertion and at rest,fatigue, sleepiness, morning headache, and difficulties withconcentration and mood changes.

Chest wall disorders are a group of thoracic deformities that result ininefficient coupling between the respiratory muscles and the thoraciccage. The disorders are usually characterised by a restrictive defectand share the potential of long term hypercapnic respiratory failure.Scoliosis and/or kyphoscoliosis may cause severe respiratory failure.Symptoms of respiratory failure include: dyspnea on exertion, peripheraloedema, orthopnea, repeated chest infections, morning headaches,fatigue, poor sleep quality and loss of appetite.

Otherwise healthy individuals may take advantage of systems and devicesto prevent respiratory disorders from arising.

2.2.1 Therapy

Nasal Continuous Positive Airway Pressure (CPAP) therapy has been usedto treat Obstructive Sleep Apnea (OSA). The hypothesis is thatcontinuous positive airway pressure acts as a pneumatic splint and mayprevent upper airway occlusion by pushing the soft palate and tongueforward and away from the posterior oropharyngeal wall.

Non-invasive ventilation (NIV) provides ventilator support to a patientthrough the upper airways to assist the patient in taking a full breathand/or maintain adequate oxygen levels in the body. The ventilatorsupport is provided via a patient interface. NIV has been used to treatCSR, OHS, COPD, MD and Chest Wall disorders.

Invasive ventilation (IV) provides ventilatory support to patients thatare no longer able to effectively breathe themselves and is providedusing a tracheostomy tube.

Ventilators may control the timing and pressure of breaths pumped intothe patient, and monitor the breaths taken by the patient. The methodsof control and monitoring patients typically include volume-cycled andpressure-cycled methods. The volume-cycled methods may include amongothers. Pressure-Regulated Volume Control (PRVC), Volume Ventilation(VV), and Volume Controlled Continuous Mandatory Ventilation (VC-CMV)techniques. The pressure-cycled methods may involve, among others.Assist Control (AC). Synchronized Intermittent Mandatory Ventilation(SIMV), Controlled Mechanical Ventilation (CMV), Pressure SupportVentilation (PSV), Continuous Positive Airway Pressure (CPAP), orPositive End Expiratory Pressure (PEEP) techniques.

2.2.2 Systems

A treatment system may comprise a Respiratory Pressure Therapy Device(RPT device), an air circuit, a humidifier, a patient interface, anddata management.

2.2.3 Patient Interface

A patient interface may be used to interface respiratory equipment toits user, for example by providing a flow of air. The flow of air may beprovided via a mask to the nose and/or mouth, or via a tracheostomy tubeto the trachea of the user. Depending upon the therapy to be applied,the patient interface may form a seal, e.g. with a face region of thepatient, to facilitate the delivery of air at a pressure at sufficientvariance with ambient pressure to effect therapy, e.g. a positivepressure of about 10 cmH2O. For other forms of therapy, such as thedelivery of oxygen, the patient interface may not include a sealsufficient to facilitate delivery to the airways of a supply of air at apositive pressure of about 10 cmH2O. Some masks suffer from being one ormore of obtrusive, aesthetically undesirable, costly, poorly fitting,difficult to use, and uncomfortable especially when worn for longperiods of time or when a patient is unfamiliar with a system. Masksdesigned solely for aviators as part of personal protection equipment orfor the administration of anaesthetics may be tolerable for theiroriginal application, but nevertheless be undesirably uncomfortable tobe worn for extended periods, for example, while sleeping or throughoutthe day.

2.2.4 Respiratory Pressure Therapy (RPT) device

One known RPT device used for treating sleep disordered breathing is theS9 Sleep Therapy System, manufactured by ResMed. Another example of anRPT device is a ventilator. Ventilators such as the ResMed Stellar™Series of Adult and Paediatric Ventilators may provide support forinvasive and non-invasive non-dependent ventilation for a range ofpatients for treating a number of conditions such as but not limited toNMD, OHS and COPD.

The ResMed Elisée™ 150 ventilator and ResMed VS III™ ventilator mayprovide support for invasive and non-invasive dependent ventilationsuitable for adult or paediatric patients for treating a number ofconditions. These ventilators provide volumetric and barometricventilation modes with a single or double limb circuit.

RPT devices typically comprise a pressure generator, such as amotor-driven blower or a compressed gas reservoir, and are configured tosupply a flow of air to the airway of a patient. In some cases, the flowof air may be supplied to the airway of the patient at positivepressure. The outlet of the RPT device is connected via an air circuitto a patient interface such as those described above.

RPT devices typically also include an inlet filter, various sensors anda microprocessor-based controller. A blower may include aservo-controlled motor, a volute and an impeller. In some cases a brakefor the motor may be implemented to more rapidly reduce the speed of theblower so as to overcome the inertia of the motor and impeller. Thebraking can permit the blower to more rapidly achieve a lower pressurecondition in time for synchronization with expiration despite theinertia. In some cases the pressure generator may also include a valvecapable of discharging generated air to atmosphere as a means foraltering the pressure delivered to the patient as an alternative tomotor speed control. The sensors measure, amongst other things, motorspeed, mass flow rate and outlet pressure, such as with a pressuretransducer or the like. The controller may include data storage capacitywith or without integrated data retrieval and display functions.

Table of noise output levels of prior RPT devices (one specimen only,measured using test method specified in ISO3744 in CPAP mode at 10cmH₂O).

A-weighted sound power Year RPT Device name level dB(A) (approx.)C-Series Tango 31.9 2007 C-Series Tango with Humidifier 33.1 2007 S8Escape II 30.5 2005 S8 Escape II with H4i Humidifier 31.1 2005 S9AutoSet 26.5 2010 S9 AutoSet with H5i Humidifier 28.6 2010

2.2.5 Humidifier

Delivery of a flow of air to a patient's airways without humidificationmay cause drying of the airways. Medical humidifiers are used toincrease humidity and/or temperature of the flow of air in relation toambient air when required, typically where the patient may be asleep orresting (e.g. at a hospital). As a result, a medical humidifier may besmall for bedside placement, and may be configured to humidify and/orheat the flow of air delivered to the patient without humidifying and/orheating the patient's surroundings. Room-based systems (e.g. a sauna, anair conditioner, an evaporative cooler), for example, may also humidifyand/or heat air that is breathed in by the patient, however they woulddo so by humidifying and/or heating the entire room, which may causediscomfort to the occupants.

The use of a humidifier with a RPT device and the patient interfaceproduces humidified air that minimizes drying of the nasal mucosa andincreases patient airway comfort. In addition in cooler climates, warmair applied generally to the face area in and about the patientinterface is more comfortable than cold air.

Respiratory humidifiers are available in many forms and may be astandalone device that is coupled to a RPT device via an air conduit, isintegrated with the RPT device or configured to be directly coupled tothe relevant RPT device. While known passive humidifiers can providesome relief, generally a heated humidifier may be used to providesufficient humidity and temperature to the air so that the patient willbe comfortable. Humidifiers typically comprise a water reservoir or tubhaving a capacity of several hundred milliliters (ml), a heating elementfor heating the water in the reservoir, a control to enable the level ofhumidification to be varied, an air inlet to receive air from the RPTdevice, and an air outlet adapted to be connected to an air circuit thatdelivers the humidified air to the patient interface.

Heated passover humidification is one common form of humidification usedwith a RPT device. In such humidifiers the heating element may beincorporated in a heater plate which sits under, and is in thermalcontact with, the water tub. Thus, heat is transferred from the heaterplate to the water reservoir primarily by conduction. The air flow fromthe RPT device passes over the heated water in the water tub resultingin water vapour being taken up by the air flow. The ResMed H4i™ and H5i™Humidifiers are examples of such heated passover humidifiers that areused in combination with ResMed S8 and S9 CPAP devices respectively.

Other humidifiers may also be used such as a bubble or diffuserhumidifier, a jet humidifier or a wicking humidifier. In a bubble ordiffuser humidifier the air is conducted below the surface of the waterand allowed to bubble back to the top. A jet humidifier produces anaerosol of water and baffles or filters may be used so that theparticles are either removed or evaporated before leaving thehumidifier. A wicking humidifier uses a water absorbing material, suchas sponge or paper, to absorb water by capillary action. The waterabsorbing material is placed within or adjacent at least a portion ofthe air flow path to allow evaporation of the water in the absorbingmaterial to be taken up into the air flow.

An alternative form of humidification is provided by the ResMedHumiCare™ D900 humidifier that uses a CounterStream™ technology thatdirects the air flow over a large surface area in a first directionwhilst supplying heated water to the large surface area in a secondopposite direction. The ResMed HumiCare™ D900 humidifier may be usedwith a range of invasive and non-invasive ventilators.

Typically, the heating element is incorporated in a heater plate whichsits under, and is in thermal contact with, the water tub. Thus, heat istransferred from the heater plate to the water reservoir primarily byconduction.

3 BRIEF SUMMARY OF THE TECHNOLOGY

The present technology is directed towards providing medical devicesused in the diagnosis, amelioration, treatment, or prevention ofrespiratory disorders having one or more of improved comfort, cost,efficacy, ease of use and manufacturability.

A first aspect of the present technology relates to apparatus used inthe diagnosis, amelioration, treatment or prevention of a respiratorydisorder.

Another aspect of the present technology relates to apparatus fortreating a respiratory disorder including a patient interface, an aircircuit, and a source of air at positive pressure.

Another aspect of the present technology relates to methods used in thediagnosis, amelioration, treatment or prevention of a respiratorydisorder.

One aspect of the present technology relates to an apparatus forhumidifying a flow of air, comprising a heater plate, a chamber in fluidcommunication with the flow of air and a reservoir comprising aconductive portion in thermal engagement with the heater plate, theapparatus configured so that varying a first pressure of the flow of airin the chamber varies a level of thermal engagement between theconductive portion and the heater plate.

In one form, the reservoir further comprises an inlet and an outlet.

In one form, the thermal engagement is in a first direction that issubstantially normal to a surface of the conductive portion.

In one form, the apparatus is further configured to vary a magnitude ofa force between the conductive portion and the heater plate in the firstdirection as the first pressure is varied.

In one form, the chamber is part of the reservoir.

In one form, the chamber further comprises a compliant portion.

In one form, the apparatus further comprises a dock configured toreceive the reservoir, and the dock comprises the heater plate.

In one form, the dock further comprises a cavity having a top portionand a bottom portion, the bottom portion having the heater plate locatedthereon, the cavity configured to retain at least a portion of thereservoir therein.

In one form, the compliant portion is compressed to enable insertion ofthe reservoir into the cavity of the dock.

In one form, the top portion of the cavity is moveable between an openand closed configuration to facilitate insertion of the reservoir intothe cavity.

In one form, the compliant portion is configured to adjust in size asthe first pressure is varied to vary the level of thermal engagementbetween the heater plate and the conductive portion.

In one form, the reservoir further includes a base and a lid, the basestructured to hold a volume of liquid and including the conductiveportion.

In one form, the base and lid are pivotably coupled together.

In one form, the compliant portion forms a seal between the base andlid.

In one form, the reservoir further includes a latch to secure the baseand lid together.

In one form, the reservoir further comprises at least one handle tofacilitate coupling of the reservoir to the dock.

In one form, the reservoir further includes a retaining clip adapted toengage with a recess on the dock to retain the reservoir in the cavityof the dock.

In one form, the reservoir is structured to prevent refilling of thereservoir when the reservoir is coupled to the dock.

In one form, at least a portion of the reservoir is prevented from beingopened when the reservoir is coupled to the dock.

In one form, the reservoir includes a re-filling cap.

In one form, the apparatus further comprises an overfill protectionelement configured to prevent filling the reservoir above apredetermined maximum volume of water.

In one form, the overfill protection element comprises at least oneorifice formed in a wall of the reservoir, the at least one orificedefines an egress path of water when the predetermined maximum volume ofwater is exceeded.

In one form, the overfill protection element comprises a sloped profilein the side profile of a wall of the reservoir, the sloped profiledefines an egress path of water when the predetermined maximum volume ofwater is exceeded.

One aspect of the present technology relates to a method for varyingthermal contact between a heater plate and a reservoir in ahumidification system for humidifying a flow of air, the methodcomprising varying a pressure of the flow of air in the reservoir thatis in fluid communication with the flow of air to vary a force betweenthe heater plate and the reservoir.

Another aspect of the present technology relates to an apparatus forhumidifying a flow of air, comprising a heater plate and a reservoircomprising an inlet to receive the flow of air, an outlet and aconductive portion in thermal contact with the heater plate, and whereinthe apparatus is configured so that varying a pressure of the flow ofair in the reservoir varies a force between the heater plate and theconductive portion in a direction of thermal contact.

In one form, the apparatus further comprises a dock connectable with thereservoir.

In one form, the dock is configured to constrain the reservoir fromopening in the direction of thermal contact.

Another aspect of the present technology relates to a reservoirconfigured to contain a volume of liquid for humidifying a pressurisedflow of air, comprising a base portion comprising a conductive portion,a lid portion comprising an inlet and an outlet and a compliant portionwherein the base portion and the lid portion are pivotably engaged andconfigurable in an open configuration and a closed configuration whilepivotably engaged, and the seal sealingly engages the base portion andthe lid portion when the reservoir is in the closed configuration.

In one form, the compliant portion comprises an outlet tube, and abaffle, the baffle being configured to connect to the inlet tube.

Another aspect of the present technology relates to an apparatus forhumidifying a flow of air, comprising a heater plate and a reservoircomprising an inlet, an outlet, a compliant portion and a conductiveportion in thermal contact with the heater plate, wherein the apparatusis configured so that varying a height of the compliant portion varies alevel of thermal engagement between the conductive portion and theheater plate.

In one form, the apparatus is configured so that the thermal engagementis in a first direction that is substantially normal to a surface of theconductive portion.

Another aspect of the present technology relates to a method of varyinga level of thermal engagement in a humidifier apparatus, the methodcomprising (i) thermally engaging a heater plate with a conductiveportion of a reservoir and (ii) varying a height of a compliant portionof the reservoir to vary a level of thermal engagement between theconductive portion and the heater plate.

Another aspect of the present technology relates to a water reservoirfor an apparatus for humidifying a flow of air, including a base portionconfigured to hold a predetermined maximum volume of water, the baseportion including an overfill protection element configured and arrangedto prevent filling the base portion above the maximum volume of water.

In one form, the water reservoir further comprises a lid portion movablyconnected to the base portion to allow the water reservoir to beconvertible between an open configuration and a closed configuration.

In one form, the overfill protection element is configured and arrangedto prevent filling the base portion above the maximum volume of waterwhen the water reservoir is in the open configuration and/or the closedconfiguration.

In one form, the water reservoir further comprises a compliant portionconfigured to sealingly engage the lid portion and the base portion whenthe reservoir is in the closed configuration.

In one form, the compliant portion is configured to block or seal theoverfill protection element to prevent fluid communication into and outof the reservoir.

In one form, the overfill protection element is configured so thatexcess water above the maximum volume of water will spill out via theoverfill protection element when the maximum volume of water is exceededand the base portion is in its normal, working orientation.

In one form, the overfill protection element comprises at least oneorifice that defines an egress path of water when the maximum volume ofwater is exceeded.

In one form, the overfill protection element is configured such thatwater only spills out through the at least one orifice when the maximumvolume of water is exceeded.

In one form, the at least one orifice is provided in one or morepositions along a perimeter of the base portion.

In one form, the at least one orifice is provided through an upper lipor flange provided along a perimeter of the base portion.

In one form, the at least one orifice includes one or more apertures,holes, slits, or slots that allows fluid communication into and out ofthe reservoir.

In one form, the water reservoir further comprises a compliant portionconfigured to sealingly engage the base portion when the reservoir is ina closed configuration, wherein the compliant portion is configured toblock or seal the at least one orifice to prevent fluid communicationinto and out of the reservoir.

In one form, the compliant portion sealing engages the base on anoutside of the at least one orifice.

In one form, the overfill protection element comprises a sloped profilein a side profile of the base portion that defines an egress path ofwater when the maximum volume of water is exceeded.

In one form, the sloped profile extends in one or more directions.

In one form, the overfill protection element is configured such thatwater only spills out through the sloped profile when the maximum volumeof water is exceeded.

In one form, the water reservoir further comprises a compliant portionconfigured to sealingly engage the base portion when the reservoir is ina closed configuration, wherein the compliant portion is configured toblock or seal the sloped profile to prevent fluid communication into andout of the reservoir.

In one form, the compliant portion sealing engages the base on an outeredge of the sloped profile.

In one form, the overfill protection element is configured and arrangedto prevent filling the base portion above the maximum volume of waterwhen the water reservoir is in the open configuration.

In one form, the overfill protection element is configured and arrangedto prevent filling the base portion above the maximum volume of waterwhen the water reservoir is in the closed configuration.

In one form, the overfill protection element forms one or more air locksto prevent further ingress of water into the base portion when themaximum volume of water is reached.

In one form, the water reservoir further comprises a lid portion movablyconnected to the base portion to allow the water reservoir to beconvertible between an open configuration and a closed configuration.

In one form, the overfill protection element is configured and arrangedto form the one or more air locks when the water reservoir is in theclosed configuration.

In one form, the water reservoir further comprises an inlet tube and anoutlet tube in communication with the base portion, the inlet tube andthe outlet tube being arranged such that, when the maximum volume ofwater is reached, air in the reservoir is prevented from escapingthrough the inlet tube and the outlet tube thereby preventing furtheringress of water into the base portion.

Another aspect of the present technology relates to an apparatus forhumidifying a flow of air, comprising a water reservoir dock and thewater reservoir substantially described as above provided to the waterreservoir dock.

In one form, the water reservoir dock forms a cavity to receive thewater reservoir.

In one form, the water reservoir dock includes a heater plate adapted tothermally engage a conductive portion provided to the water reservoir.

Another aspect of the present technology relates to a method ofpreventing overfilling in a humidifier reservoir, the method comprising(i) incorporating an overfill protection element in a base portion ofthe humidifier reservoir and (ii) configuring the overfill protectionelement so that excess water above a predetermined maximum volume ofwater will spill out via the overfill protection element when themaximum volume of water is exceeded and the base portion is in itsnormal, working orientation.

In one form, the overfill protection element includes at least oneorifice.

In one form, the overfill protection element includes a sloped profile.

In one form, the method of preventing overfilling in a humidifierreservoir further comprises configuring the overfill protection elementsuch that water only spills via the overfill protection element when themaximum volume of water is exceeded.

Another aspect of the present technology relates to a reservoirconfigured to hold a predetermined maximum volume of water, comprising aplurality of walls forming a cavity structured to hold the predeterminedmaximum volume of water, an inlet tube configured to deliver a supply ofair into the cavity, the inlet tube having an inlet interior end and aninlet exterior end and an outlet tube configured to deliver a humidifiedsupply of air from the cavity, the outlet tube having an outlet interiorend and an outlet exterior end, wherein the inlet interior end and theoutlet interior end are located within the cavity and the inlet exteriorend and the outlet exterior end are located in one of the plurality ofwalls of the cavity, a first axis defined by the inlet interior end andthe inlet exterior end and a second axis defined by the outlet interiorend and the outlet exterior end, wherein when the reservoir is tiltedapproximately 90° to normal working orientation the first axis is on afirst angle such that the inlet interior end and the inlet exterior endare positioned at different heights, such that the predetermined maximumvolume of water is below at least one of the inlet interior end or theinlet exterior end to prevent spillback of water through the inlet tube.

In one form, the reservoir is further configured so that when thereservoir is tilted approximately 90° to normal working orientation thesecond axis is on a second angle such that the outlet interior end andthe outlet exterior end are positioned at different heights, such thatthe predetermined maximum volume of water is below at least one of theoutlet interior end or the outlet exterior end to prevent spillback ofwater through the outlet tube.

Of course, portions of the aspects may form sub-aspects of the presenttechnology. Also, various ones of the sub-aspects and/or aspects may becombined in various manners and also constitute additional aspects orsub-aspects of the present technology.

Other features of the technology will be apparent from consideration ofthe information contained in the following detailed description,abstract, drawings and claims.

4 BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The present technology is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings, in whichlike reference numerals refer to similar elements including:

4.1 Treatment Systems

FIG. 1 a shows a system including a patient 1000 wearing a patientinterface 3000, in the form of nasal pillows, receives a supply of airat positive pressure from a RPT device 4000. Air from the RPT device ishumidified in a humidifier 5000, and passes along an air circuit 4170 tothe patient 1000.

FIG. 1 b shows a system including a patient 1000 wearing a patientinterface 3000, in the form of a nasal mask, receives a supply of air atpositive pressure from a RPT device 4000. Air from the RPT device ishumidified in a humidifier 5000, and passes along an air circuit 4170 tothe patient 1000.

FIG. 1 c shows a system including a patient 1000 wearing a patientinterface 3000, in the form of a full-face mask, receives a supply ofair at positive pressure from a RPT device. Air from the RPT device ishumidified in a humidifier 5000, and passes along an air circuit 4170 tothe patient 1000.

4.2 Therapy

4.2.1 Respiratory system

FIG. 2 a shows an overview of a human respiratory system including thenasal and oral cavities, the larynx, vocal folds, oesophagus, trachea,bronchus, lung, alveolar sacs, heart and diaphragm.

FIG. 2 b shows a view of a human upper airway including the nasalcavity, nasal bone, lateral nasal cartilage, greater alar cartilage,nostril, lip superior, lip inferior, larynx, hard palate, soft palate,oropharynx, tongue, epiglottis, vocal folds, oesophagus and trachea.

4.3 Patient Interface

FIG. 3 a shows a patient interface in accordance with one form of thepresent technology.

4.4 Respiratory Apparatus

FIG. 4 a shows a RPT device in accordance with one form of the presenttechnology.

FIG. 4 b shows a schematic diagram of the pneumatic circuit of a RPTdevice in accordance with one form of the present technology. Thedirections of upstream and downstream are indicated.

FIG. 4 c shows a schematic diagram of the electrical components of a RPTdevice in accordance with one aspect of the present technology.

FIG. 4 d shows a schematic diagram of the algorithms implemented in aRPT device in accordance with an aspect of the present technology. Inthis figure, arrows with solid lines indicate an actual flow ofinformation, for example via an electronic signal.

FIG. 4 e is a flow chart illustrating a method carried out by thetherapy engine of FIG. 4 d in accordance with one aspect of the presenttechnology.

4.5 Humidifier

FIG. 5 a shows a simplified representation of a humidifier connected toa pressure generator 4140 via an air circuit 4170.

FIG. 5 b shows a schematic of a humidifier.

4.6 Breathing Waveforms

FIG. 6 a shows a model typical breath waveform of a person whilesleeping. The horizontal axis is time, and the vertical axis isrespiratory flow. While the parameter values may vary, a typical breathmay have the following approximate values:tidal volume. Vt, 0.5 L,inhalation time, Ti. 1.6 s, peak inspiratory flow, Qpeak, 0.4 L/s,exhalation time, Te, 2.4 s, peak expiratory flow, Qpeak, −0.5 L/s. Thetotal duration of the breath, Ttor, is about 4 s. The person typicallybreathes at a rate of about 15 breaths per minute (BPM), withVentilation. Vent, about 7.5 L/minute. A typical duty cycle, the ratioof Ti to Trot is about 40%.

4.7 RPT Device with a Humidifier

FIG. 7 shows a prior art example of a RPT device 4000 and a humidifier5000.

FIG. 8 shows a RPT device 4000 and an integrated humidifier 5000according to an example of the present technology.

FIGS. 9 to 12 show various views of a humidifier reservoir 5110 inaccordance with an example of present technology, wherein FIGS. 9 to 10show the humidifier reservoir 5110 in a ‘closed’ configuration, FIG. 11shows the humidifier reservoir 5110 in an ‘open’ configuration and FIG.12 is an exploded view of the humidifier reservoir 5110.

FIGS. 13 to 16 show the humidifier 5000 from various perspectives,demonstrating the engagement of the humidifier reservoir 5110 with thereservoir dock 5130 and/or engagement of the humidifier 5000 with theair circuit 4170 according to an example of the present technology.

FIGS. 17 a to 17 c, 18 a to 18 c, and 19 a to 19 c show a time-lapsechart of an exemplary flow path of air as it enters the humidifierreservoir 5110 through the inlet 5118 (FIGS. 17 a to 17 c) and exitsthrough the outlet 5122 (FIGS. 19 a to 19 c) after traversing throughthe inside of the humidifier reservoir 5110 (FIGS. 18 a to 18 c)according to an example of the present technology.

FIGS. 20 to 21 show exemplary distributions of pressure/force in thehumidifier reservoir 5110 in various configurations according to anexample of the present technology.

FIGS. 22 to 29 show varying configurations of the reservoir lid 5114, inparticular variations in configurations of the inlet tube 5124 and theoutlet tube 5126 according to examples of the present technology.

FIGS. 30 a and 30 b show the humidifier reservoir 5110 and in particularthe orifices 5138 according to an example of the present technology.

FIGS. 30 c and 30 d show the humidifier base 5112 and in particular thesloped profile 5139 according to an example of the present technology.

FIG. 31 a shows the humidifier reservoir 5110 and in particular theorifice 5138 according to an example of the present technology.

FIG. 31 b shows the humidifier reservoir 5110 and in particular thesloped profile 5139 according to an example of the present technology.

FIGS. 32 to 33 show the humidifier dock 5130 and the humidifierreservoir 5110, and in particular show the interaction between the lidretention protrusion 5142 and the dock locking recess 5144 according toan example of the present technology.

FIG. 34 shows the humidifier reservoir 5110 according to another exampleof the present technology, wherein it is configured with a re-fillingcap 5180 and a base, top and compliant portion may be affixed together.

FIGS. 35 to 38 show other representations of a humidifier reservoir 5110according to an example of the present technology, with particularregard to the arrangement of the inlet tube 5124 and the outlet tube5126.

FIG. 39 shows a cross-sectional view of a reservoir lid 5114 and acompliant portion 5116 according to an example of the presenttechnology.

FIG. 40 shows an example of the humidifier reservoir 5110 according toanother example of the present technology, wherein it is configured witha latch 5186.

FIGS. 41 a, 41 b, and 42 show a humidifier reservoir 5110 according toanother example of the present technology. In this configuration, thereservoir 5110 comprises a reservoir lid 5114 including an inlet tube5124, a base portion 5112 (as seen in an exploded view shown in FIG. 42)and an intermediate portion 5202 which comprises an outlet tube 5126.

FIGS. 43 a and 43 b show the intermediate portion 5202 of the reservoir5110 from various angles according to an example of the presenttechnology. In particular they aim to show the baffle 5192, the outlettube 5126 and the support spokes 5194.

FIG. 44 shows a perspective bottom view of the intermediate portion 5202of the reservoir 5110 according to an example of the present technology.

FIGS. 45 a and 45 b show a cross section of the reservoir lid 5114 andthe intermediate portion 5202 connected together, and FIG. 45 c showsthe reservoir lid 5114 indicating a cross section shown in FIGS. 45 aand 45 b, according to an example of the present technology. FIG. 45 hshows the cross section of the baffle 5192 in further detail, inparticular the arrangement of the vertical portion of the inlet tube5124, the locating portion 5196 of the baffle 5192 and the deflectorportion 5198 of the baffle 5192.

FIG. 46 shows an upper portion of the humidifier reservoir 5110according to another example of the present technology. In thisconfiguration, the reservoir 5110 comprises a reservoir lid portion5114, a base portion (not shown), and an intermediate portion 5202 thatcomprises an outlet tube 5126, an inlet tube 5124 as well as a wallportion 5206.

FIGS. 47 a and 47 b show a portion of the humidifier reservoir 5110according to another example of the present technology. FIGS. 47 a and47 b show the reservoir lid 5114 connected to the intermediate portion5202, and in particular they aim to show the inlet tube 5124, the outlettube 5126, the deflector portion 5198 and the flow director 5195.

FIGS. 48 a and 48 b show the intermediate portion 5202 according toanother example of the present technology, and in particular they aim toshow the deflector portion 5198, the flow director 5195, the locatingportion 5196 and the compliant portion 5116.

FIG. 49 shows a portion of the humidifier reservoir 5110 according toanother example of the present technology. In particular, FIG. 49 showsa water level 5184 at which the air locks would be formed to preventfurther ingress of liquid into the reservoir 5110 when the predeterminedmaximum volume of liquid is in the reservoir 5110.

FIGS. 50 a, 50 b, 51 a, and 51 b show various views of a humidifierreservoir 5110 in accordance with an example of the present technology,wherein FIGS. 50 a, 50 b, and 51 a show the humidifier reservoir 5110 ina ‘closed’ configuration, and FIG. 51 b shows the humidifier reservoir5110 in an ‘open’ configuration.

FIGS. 52 a and 52 b show various views of a humidifier reservoir 5110 inaccordance with an example of the present technology. FIG. 52 a shows aplan view of the humidifier reservoir 5110 in an ‘open configuration’,indicating a cross section to be shown in FIG. 52 b, and FIG. 52 b showsa cross section of the reservoir 5110 through line 52 b-52 b of FIG. 52a with the cross section visible.

FIGS. 53 and 54 show various views of a reservoir base 5112 inaccordance with an example of the present technology.

FIGS. 55 a and 55 b show a collapsible tube 5208 in accordance with anexample of the present technology. FIG. 55 a shows a collapsible tube5208 in an ‘open’ configuration, and FIG. 55 b shows a collapsible tube5208 in a ‘closed’ configuration.

FIG. 56 shows a humidifier reservoir lid 5114 in accordance with anexample of the present technology, wherein an inlet tube 5124 of thereservoir lid 5114 comprises a flexible portion 5210 and a rigid portion5212.

FIG. 57 a shows a side view of the humidifier reservoir 5110 (showingthe base 5112 only) in accordance with an example of the presenttechnology, indicating a cross section 57 b-57 b which is shown on FIG.57 b.

FIG. 57 b shows a perspective view of the humidifier reservoir 5110(showing the base 5112 only), showing a cross section as indicated onFIG. 57 a. In particular, FIG. 57 b shows an orifice 5138 and a waterfilling indication mark 5140.

FIG. 58 a shows a top view of the humidifier reservoir 5110 inaccordance with an example of the present technology, indicating a crosssection 58 b-58 b which is shown on FIG. 58 b.

FIG. 58 b shows a side view of the humidifier reservoir 5110, showing across section as indicated on FIG. 58 a. In particular, FIG. 58 b showsan orifice 5138, a water level at predetermined maximum volume of water5141_1 and a water level at threshold volume of water 5141_2.

FIG. 59 shows an exploded perspective view of an RPT device 4000, anintegrated humidifier 5000 and a humidifier end cap 5300 according to anexample of the present technology.

FIG. 60 shows a perspective view of a humidifier end cap 5300 accordingto an example of the present technology.

5 DETAILED DESCRIPTION OF EXAMPLES OF THE TECHNOLOGY

Before the present technology is described in further detail, it is tobe understood that the technology is not limited to the particularexamples described herein, which may vary. It is also to be understoodthat the terminology used in this disclosure is for the purpose ofdescribing only the particular examples discussed herein, and is notintended to be limiting.

The following description is provided in relation to several exampleswhich may share common characteristics and features. It is to beunderstood that one or more features of any one example may becombinable with one or more features of the other examples. In addition,any single feature or combination of features in any of the examples mayconstitute additional examples.

5.1 TREATMENT SYSTEMS

In one form, the present technology comprises an apparatus for treatinga respiratory disorder such as an RPT device. The apparatus or devicemay comprise a pressure generator or blower for supplying a flow of air,to the patient 1000 via an air circuit leading to a patient interface3000.

5.2 THERAPY

In one form, the present technology comprises a method for treating arespiratory disorder comprising the step of applying positive pressureto the entrance of the airways of a patient 1000.

5.2.1 Nasal CPAP for OSA

In one form, the present technology comprises a method of treatingObstructive Sleep Apnea in a patient by applying nasal continuouspositive airway pressure to the patient.

In certain examples of the present technology, a supply of air atpositive pressure is provided to the nasal passages of the patient viaone or both nares.

5.3 PATIENT INTERFACE 3000

A non-invasive patient interface 3000 in accordance with one aspect ofthe present technology comprises the following functional aspects: aseal-forming structure 3100, a plenum chamber 3200, a positioning andstabilising structure 3300 and a connection port 3600 for connection toair circuit 4170. In some forms a functional aspect may be provided byone or more physical components. In some forms, one physical componentmay provide one or more functional aspects. In use the seal-formingstructure 3100 is arranged to surround an entrance to the airways of thepatient so as to facilitate the supply of air at positive pressure tothe airways.

5.4 RESPIRATORY APPARATUS

An RPT device 4000 in accordance with one aspect of the presenttechnology is shown in FIG. 4 a, and comprises mechanical and pneumaticcomponents 4100, electrical components 4200 and is programmed to executeone or more algorithms 4300. The RPT device may comprise an externalhousing 4010 which may be formed in two parts, an upper portion 4012 anda lower portion 4014. Furthermore, the external housing 4010 may includeone or more panel(s) 4015. The RPT device 4000 may comprise a chassis4016 that supports one or more internal components of the RPT device4000. In one form a pneumatic block 4020 is supported by, or formed aspart of the chassis 4016. The RPT device 4000 may include a handle 4018.

A schematic diagram of a pneumatic circuit of the RPT device 4000according to an example of the present technology is shown in FIG. 4 b.The pneumatic path of the RPT device 4000 may comprise an inlet airfilter 4112, an inlet muffler 4122, a pressure generator 4140 capable ofsupplying air at positive pressure (preferably a blower 4142), apneumatic block 4020 and an outlet muffler 4124. One or more transducers4270, such as pressure sensors 4272 and flow sensors 4274 may beincluded in the pneumatic path.

The pneumatic block 4020 may comprise a portion of the pneumatic paththat is located within the external housing 4010 and may house thepressure generator 4140.

The RPT device 4000 may include an electrical power supply 4210, one ormore input devices 4220, a central controller 4230, a therapy devicecontroller 4240, a pressure generator 4140, one or more protectioncircuits 4250, memory 4260, transducers 4270, data communicationinterface 4280 and one or more output devices 4290. Electricalcomponents 4200 may be mounted on a single Printed Circuit BoardAssembly (PCBA) 4202. In an alternative form, the RPT device 4000 mayinclude more than one PCBA 4202.

FIG. 7 shows a prior art embodiment of a RPT device 4000, which isconnectable to a humidifier 5000. The RPT device may also be integratedwith a humidifier 5000 so that an external housing 4010 encases thecomponents that perform the equivalent function of a RPT device 4000 aswell as components that perform the equivalent function of a humidifier5000.

FIG. 8 shows an embodiment of such an integrated device comprising a RPTdevice 4000 and a humidifier 5000 according to an example of the presenttechnology. It should be understood that subsequent references to ahumidifier 5000 refers to the integrated device, in particular thecomponents that perform the equivalent function of a humidifier 5000.

5.4.1 RPT Device Mechanical & Pneumatic Components 4100 5.4.1.1 AirFilter(s) 4110

A RPT device in accordance with one form of the present technology mayinclude one or more air filters 4110.

In one form, an inlet air filter 4112 is located at the beginning of thepneumatic path upstream of a blower 4142. See FIG. 4 b.

In one form, an outlet air filter 4114, for example an antibacterialfilter, is located between an outlet of the pneumatic block 4020 and apatient interface 3000. See FIG. 4 b.

5.4.1.2 Muffler(s) 4120

In one form of the present technology, an inlet muffler 4122 is locatedin the pneumatic path upstream of a blower 4142. See FIG. 4 b.

In one form of the present technology, an outlet muffler 4124 is locatedin the pneumatic path between the blower 4142 and a patient interface3000. See FIG. 4 b.

5.4.13 Pressure Generator 4140

In a preferred form of the present technology, a pressure generator 4140for producing a flow of air at positive pressure is a blower 4142. Forexample the blower may include a brushless DC motor 4144 with one ormore impellers housed in a volute. The blower may preferably be capableof delivering a supply of air, for example up to about 120litres/minute, at a positive pressure in a range from about 4 cm H₂O toabout 20 cm H₂O, or in other forms up to about 30 cm H₂O. Examples of asuitable blower may include a blower as described in any one of thefollowing patents or patent applications the contents of which areincorporated herein in their entirety: U.S. Pat. No. 7,866,944; U.S.Pat. No. 8,638,014; U.S. Pat. No. 8,636,479; and PCT patent applicationpublication number WO 2013/020167.

The pressure generator 4140 is under the control of the therapy devicecontroller 4240.

In other forms, a pressure generator 4140 may be a piston-driven pump, apressure regulator connected to a high pressure source (e.g. compressedair reservoir), or a bellows.

5.4.1.4 Transducer(s) 4270

Transducers may be internal of the RPT device, or external of the RPTdevice. External transducers may be located for example on or form partof the air circuit, e.g. the patient interface. External transducers maybe in the form of non-contact sensors such as a Doppler radar movementsensor that transmit or transfer data to the RPT device.

In one form of the present technology, one or more transducers 4270 arelocated in the pneumatic path, such as upstream and/or downstream of thepressure generator 4140. The one or more transducers 4270 areconstructed and arranged to measure properties such as flow rate, apressure, a temperature or a humidity of the flow of air at that pointin the pneumatic path.

In one form of the present technology, one or more transducers 4270 arelocated proximate to the patient interface 3000, such as in the aircircuit 4170.

In another form of the present technology, one or more transducer 4270may be arranged to measure properties of the ambient air.

In one form, a signal from a transducer 4270 may be filtered, such as bylow-pass, high-pass or band-pass filtering.

5.4.1.4.1 Flow Transducer 4274

A flow rate transducer 4274 in accordance with the present technologymay be based on a differential pressure transducer, for example, anSDP600 Series differential pressure transducer from SENSIRION.

In one form, a signal representing a flow rate such as a total flow Qtfrom the flow transducer 4274 is received by the central controller4230.

5.4.1.4.2 Pressure Transducer 4272

A pressure transducer 4272 in accordance with the present technology islocated in fluid communication with the pneumatic path. An example of asuitable pressure transducer is a sensor from the HONEYWELL ASDX series.An alternative suitable pressure transducer is a sensor from the NPASeries from GENERAL ELECTRIC.

In one form, a signal from the pressure transducer 4272 is received bythe central controller 4230.

5.4.1.4.3 Motor Speed Transducer 4276

In one form of the present technology a motor speed transducer 4276 isused to determine a rotational velocity of the motor 4144 and/or theblower 4142. A motor speed signal from the motor speed transducer 4276is preferably provided to the therapy device controller 4240. The motorspeed transducer 4276 may, for example, be a speed sensor, such as aHall effect sensor.

5.4.1.5 Anti-Spillback Valve 4160

In one form of the present technology, an anti-spillback valve islocated between the humidifier 5000 and the pneumatic block 4020. Theanti-spill back valve is constructed and arranged to reduce the riskthat water will flow upstream from the humidifier 5000, for example tothe motor 4144.

5.4.1.6 Air Circuit 4170

An air circuit 4170 in accordance with an aspect of the presenttechnology is a conduit or a tube constructed and arranged in use toallow a flow of air to travel between two components such as thepneumatic block 4020 and the patient interface 3000.

In particular, the air circuit 4170 may be in fluid connection with theoutlet of the pneumatic block and the patient interface. The air circuitmay be referred to as an air delivery tube. In some cases there may beseparate limbs of the circuit for inhalation and exhalation. In othercases a single limb is used.

5.4.1.7 Supplemental Oxygen 4180

In one form of the present technology, supplemental oxygen 4180 isdelivered to one or more points in the pneumatic path, such as upstreamof the pneumatic block 4020, to the air circuit 4170 and/or to thepatient interface 3000.

5.4.1.7.1 Power Supply 4210

A power supply (or PSU) 4210 may be located internal or external of theexternal housing 4010 of the RPT device 4000.

In one form of the present technology power supply 4210 provideselectrical power to the RPT device 4000 only. In another form of thepresent technology, power supply 4210 provides electrical power to bothRPT device 4000 and humidifier 5000.

5.4.1.7.2 Input Devices 4220

In one form of the present technology, a RPT device 4000 includes one ormore input devices 4220 in the form of buttons, switches or dials toallow a person to interact with the device. The buttons, switches ordials may be physical devices, or software devices accessible via atouch screen. The buttons, switches or dials may, in one form, bephysically connected to the external housing 4010, or may, in anotherform, be in wireless communication with a receiver that is in electricalconnection to the central controller 4230.

In one form the input device 4220 may be constructed and arranged toallow a person to select a value and/or a menu option.

5.4.1.7.3 Central Controller 4230

In one form of the present technology, the central controller 4230 isone or a plurality of processors suitable to control a RPT device 4000.

Suitable processors may include an x86 INTEL processor, a processorbased on ARM Cortex-M processor from ARM Holdings such as an STM32series microcontroller from ST MICROELECTRONIC. In certain alternativeforms of the present technology, a 32-bit RISC CPU, such as an STR9series microcontroller from ST MICROELECTRONICS or a 16-bit RISC CPUsuch as a processor from the MSP430 family of microcontrollers,manufactured by TEXAS INSTRUMENTS may also be suitable.

In one form of the present technology, the central controller 4230 is adedicated electronic circuit.

In one form, the central controller 4230 is an application-specificintegrated circuit. In another form, the central controller 4230comprises discrete electronic components.

The central controller 4230 may be configured to receive input signal(s)from one or more transducers 4270, and one or more input devices 4220.

The central controller 4230 may be configured to provide outputsignal(s) to one or more of an output device 4290, a therapy devicecontroller 4240, a data communication interface 4280 and humidifiercontroller 5250.

In some forms of the present technology, the central controller 4230 isconfigured to implement the one or more methodologies described hereinsuch as the one or more algorithms 4300. In some forms of the presenttechnology, the central controller 4230 may be integrated with a RPTdevice 4000. However, in some forms of the present technology, thecentral controller 4230 may be implemented discretely from the flowgeneration components of the RPT device 4000, such as for purpose ofperforming any of the methodologies described herein without directlycontrolling delivery of a respiratory treatment. For example, thecentral controller 4230 may perform any of the methodologies describedherein for purposes of determining control settings for a ventilator orother respiratory related events by analysis of stored data such as fromany of the transducers 4270 described herein.

5.4.1.7.4 Clock 4232

Preferably RPT device 4000 includes a clock 4232 that is connected tothe central controller 4230.

5.4.1.7.5 Therapy Device Controller 4240

In one form of the present technology, therapy device controller 4240 isa control module 4330 that forms part of the algorithms 4300 executed bythe central controller 4230.

In one form of the present technology, therapy device controller 4240 isa dedicated motor control integrated circuit. For example, in one form aMC33035 brushless DC motor controller, manufactured by ONSEMI is used.

5.4.1.7.6 Protection Circuits 4250

The one or more protection circuits 4250 in accordance with the presenttechnology may comprise an electrical protection circuit, a temperatureand/or pressure safety circuit.

5.4.1.7.7 Memory 4260

In accordance with one form of the present technology the RPT device4000 includes memory 4260, preferably non-volatile memory. In someforms, memory 4260 may include battery powered static RAM. In someforms, memory 4260 may include volatile RAM.

Preferably memory 4260 is located on the PCBA 4202. Memory 4260 may bein the form of EEPROM, or NAND flash.

Additionally or alternatively, RPT device 4000 includes a removable formof memory 4260, for example a memory card made in accordance with theSecure Digital (SD) standard.

In one form of the present technology, the memory 4260 acts as anon-transitory computer readable storage medium on which is storedcomputer program instructions expressing the one or more methodologiesdescribed herein, such as the one or more algorithms 4300.

5.4.1.8 Data Communication Systems 4280

In one preferred form of the present technology, a data communicationinterface 4280 is provided, and is connected to the central controller4230. Data communication interface 4280 is preferably connectable toremote external communication network 4282 and/or a local externalcommunication network 4284.

Preferably remote external communication network 4282 is connectable toremote external device 4286. Preferably local external communicationnetwork 4284 is connectable to local external device 4288.

In one form, data communication interface 4280 is part of the centralcontroller 4230. In another form, data communication interface 4280 isseparate from the central controller 4230, and may comprise anintegrated circuit or a processor.

In one form, remote external communication network 4282 is the Internet.The data communication interface 4280 may use wired communication (e.g.via Ethernet, or optical fibre) or a wireless protocol (e.g. CDMA, GSM,LTE) to connect to the Internet.

In one form, local external communication network 4284 utilises one ormore communication standards, such as Bluetooth, or a consumer infraredprotocol.

In one form, remote external device 4286 is one or more computers, forexample a cluster of networked computers. In one form, remote externaldevice 4286 may be virtual computers, rather than physical computers. Ineither case, such remote external device 4286 may be accessible to anappropriately authorised person such as a clinician.

Preferably local external device 4288 is a personal computer, mobilephone, tablet or remote control.

5.4.1.9 Output Devices 4290 (Including Optional Display, Alarms)

An output device 4290 in accordance with the present technology may takethe form of one or more of a visual, audio and haptic unit. A visualdisplay may be a Liquid Crystal Display (LCD) or Light Emitting Diode(LED) display.

5.4.1.9.1 Display Driver 4292

A display driver 4292 receives as an input the characters, symbols, orimages intended for display on the display 4294, and converts them tocommands that cause the display 4294 to display those characters,symbols, or images.

5.4.1.9.2 Display 4294

A display 4294 is configured to visually display characters, symbols, orimages in response to commands received from the display driver 4292.For example, the display 4294 may be an eight-segment display, in whichcase the display driver 4292 converts each character or symbol, such asthe figure “0”, to eight logical signals indicating whether the eightrespective segments are to be activated to display a particularcharacter or symbol.

5.4.2 RPT Device Algorithms 4300 5.4.2.1 Pre-Processing Module 4310

A pre-processing module 4310 in accordance with one form of the presenttechnology receives as an input a signal from a transducer 4270, forexample a flow transducer 4274 or pressure transducer 4272, andpreferably performs one or more process steps to calculate one or moreoutput values that will be used as an input to another module, forexample a therapy engine module 4320.

In one form of the present technology, the output values include thepatient interface or mask pressure Pm, the respiratory flow Qr, and theunintentional leak flow Ql.

In various forms of the present technology, the pre-processing module4310 comprises one or more of the following algorithms: pressurecompensation algorithm 4312, vent flow algorithm 4314 (e.g. intentionalleak), leak flow algorithm 4316 (e.g. unintentional leak) andrespiratory flow algorithm 4318.

5.4.2.1.1 Pressure Compensation 4312

In one form of the present technology, a pressure compensation algorithm4312 receives as an input a signal indicative of the pressure in thepneumatic path proximal to an outlet of the pneumatic block. Thepressure compensation algorithm 4312 estimates the pressure drop throughthe air circuit 4170 and provides as an output an estimated pressure,Pm, in the patient interface 3000.

5.4.2.1.2 Vent Flow 4314

In one form of the present technology, a vent flow calculation algorithm4314 receives as an input an estimated pressure, Pm, in the patientinterface 3000 and estimates a vent flow of air, Qv, from a vent 3400 ina patient interface 3000.

5.4.2.1.3 Leak Flow 4316

In one form of the present technology, a leak flow algorithm 4316receives as an input a total flow, Qt, and a vent flow Qv, and providesas an output an estimate of the unintentional leak, i.e. leak flow, Ql,by calculating an average of Qt-Qv over a period sufficiently long toinclude several breathing cycles, e.g. about 10 seconds.

In one form, the leak flow algorithm 4316 receives as an input a totalflow Qt, a vent flow Qv, and an estimated pressure, Pm, in the patientinterface 3000, and provides as an output a leak flow Ql by calculatinga leak conductance, and determining a leak flow Ql to be a function ofleak conductance and pressure. Pm. Preferably leak conductance iscalculated as the quotient of low pass filtered non-vent flow Qt Qv, andlow pass filtered square root of pressure Pm, where the low pass filtertime constant has a value sufficiently long to include several breathingcycles. e.g. about 10 seconds.

5.4.2.1.4 Respiratory Flow 4318

In one form of the present technology, a respiratory flow algorithm 4318receives as an input a total flow, Qt, a vent flow, Qv, and a leak flow,Ql, and estimates a respiratory flow of air, Qr, to the patient, bysubtracting the vent flow Qv and the leak flow Ql from the total flowQt.

5.4.2.2 Therapy Engine Module 4320

In one form of the present technology, a therapy engine module 4320receives as inputs one or more of a pressure, Pm, in a patient interface3000, and a respiratory flow of air to a patient, Qr, and provides as anoutput, one or more therapy parameters.

In one form of the present technology, a therapy parameter is a CPAPtreatment pressure Pt.

In one form of the present technology, a therapy parameter is one ormore of a level of pressure support and a target ventilation.

In various forms of the present technology, the therapy engine module4320 comprises one or more of the following algorithms: phasedetermination algorithm 4321, waveform determination algorithm 4322,ventilation determination algorithm 4323, flow limitation determinationalgorithm 4324. Apnea/hypopnea determination algorithm 4325. Snoredetermination algorithm 4326, Patency determination algorithm 4327 andTherapy parameter determination algorithm 4328.

5.4.2.2.1 Phase Determination 4321

In one form of the present technology, the RPT device 4000 does notdetermine phase.

In another form of the present technology, the RPT device 400 doesdetermine phase using a phase determination algorithm 4321. The phasedetermination algorithm 4321 receives as an input a signal indicative ofrespiratory flow, Qr, and provides as an output a phase of a breathingcycle of a patient 1000.

In some forms the phase output may include a discrete variable withvalues of one or more of inhalation, mid-inspiratory pause, andexhalation. For example the phase output may be determined to have adiscrete value of inhalation when a respiratory flow Qr has a positivevalue that exceeds a positive threshold and the phase may be determinedto have a discrete value of exhalation when a respiratory flow Qr has anegative value that is more negative than a negative threshold.

In other forms, the phase output may include a continuous variable, forexample varying from 0 to 1, or 0 to 2 Pi.

5.4.2.2.2 Waveform Determination 4322

In one form of the present technology, a control module 4330 controls apressure generator 4140 to provide an approximately constant positiveairway pressure throughout a respiratory cycle of a patient.

In other forms of the present technology, a control module 4330 controlsa pressure generator 4140 to provide positive airway pressure accordingto a predetermined waveform of pressure vs phase. In one form, thewaveform is maintained at an approximately constant level for all valuesof phase. In one form, the waveform is a square wave, having a highervalue for some values of phase, and a lower level for other values ofphase.

In some forms of the present technology a waveform determinationalgorithm 4322 receives as an input a value indicative of currentpatient ventilation, Vent, and provides as an output a waveform ofpressure vs. phase. For example a ventilation determination algorithm4323 may receive as an input a respiratory flow Qr, and determine ameasure indicative of patient ventilation. Vent. The current value ofpatient ventilation, Vent, may be determined as half the low-passfiltered absolute value of respiratory flow, Qr.

5.4.2.2.3 Ventilation Determination 4323

In one form of the present technology, a ventilation determinationalgorithm 4323 receives an input a respiratory flow Qr, and determines ameasure indicative of patient ventilation, Vent.

In some forms of the present technology, ventilation determinationalgorithm 4323 determines a current value of patient ventilation, Vent,as half the low-pass filtered absolute value of respiratory flow, Qr.

5.4.2.2.4 Determination of Inspiratory Flow Limitation 4324

In one form of the present technology, the central controller executesone or more algorithms 4324 for the detection of inspiratory flowlimitation.

In one form the algorithm 4324 receives as an input a respiratory flowsignal Qr and provides as an output a metric of the extent to which theinspiratory portion of the breath exhibits inspiratory flow limitation.

In one form of the present technology, the inspiratory portion of eachbreath is identified by a zero-crossing detector. A number of evenlyspaced points (for example, sixty-five), representing points in time,are interpolated by an interpolator along the inspiratory flow-timecurve for each breath. The curve described by the points is then scaledby a scaler to have unity length (duration/period) and unity area toremove the effects of changing respiratory rate and depth. The scaledbreaths are then compared in a comparator with a pre-stored templaterepresenting a normal unobstructed breath, similar to the inspiratoryportion of the breath shown in FIG. 6 a. Breaths deviating by more thana specified threshold (typically 1 scaled unit) at any time during theinspiration from this template, such as those due to coughs, sighs,swallows and hiccups, as determined by a test element, are rejected. Fornon-rejected data, a moving average of the first such scaled point iscalculated by the central controller 4230 for the preceding severalinspiratory events. This is repeated over the same inspiratory eventsfor the second such point, and so on. Thus, for example, sixty fivescaled data points are generated by the central controller 4230, andrepresent a moving average of the preceding several inspiratory events,e.g. three events. The moving average of continuously updated values ofthe (e.g. sixty five) points are hereinafter called the “scaled flow”,designated as Qs(t). Alternatively, a single inspiratory event can beutilised rather than a moving average.

From the scaled flow, two shape factors relating to the determination ofpartial obstruction may be calculated.

Shape factor 1 is the ratio of the mean of the middle (e.g. thirty-two)scaled flow points to the mean overall (e.g. sixty-five) scaled flowpoints. Where this ratio is in excess of unity, the breath will be takento be normal. Where the ratio is unity or less, the breath will be takento be obstructed. A ratio of about 1.17 is taken as a threshold betweenpartially obstructed and unobstructed breathing, and equates to a degreeof obstruction that would permit maintenance of adequate oxygenation ina typical user.

Shape factor 2 is calculated as the RMS deviation from unit scaled flow,taken over the middle (e.g. thirty two) points. An RMS deviation ofabout 0.2 units is taken to be normal. An RMS deviation of zero is takento be a totally flow-limited breath. The closer the RMS deviation tozero, the breath will be taken to be more flow limited.

Shape factors 1 and 2 may be used as alternatives, or in combination. Inother forms of the present technology, the number of sampled points,breaths and middle points may differ from those described above.Furthermore, the threshold values can be other values than thosedescribed.

5.4.2.2.5 Determination of Apneas and Hypopneas 4325

In one form of the present technology, the central controller 4230executes one or more algorithms 4325 for the determination of thepresence of apneas and/or hypopneas.

Preferably the one or more algorithms 4325 receive as an input arespiratory flow signal Qr and provide as an output a flag thatindicates that an apnea or a hypopnea has been detected.

In one form, an apnea will be said to have been detected when a functionof respiratory flow Qr falls below a flow threshold for a predeterminedperiod of time. The function may determine a peak flow, a relativelyshort-term mean flow, or a flow intermediate of relatively short-termmean and peak flow, for example an RMS flow. The flow threshold may be arelatively long-term measure of flow.

In one form, a hypopnea will be said to have been detected when afunction of respiratory flow Qr falls below a second flow threshold fora predetermined period of time. The function may determine a peak flow,a relatively short-term mean flow, or a flow intermediate of relativelyshort-term mean and peak flow, for example an RMS flow. The second flowthreshold may be a relatively long-term measure of flow. The second flowthreshold is greater than the flow threshold used to detect apneas.

5.4.2.2.6 Determination of Snore 4326

In one form of the present technology, the central controller 4230executes one or more snore algorithms 4326 for the detection of snore.

In one form the snore algorithm 4326 receives as an input a respiratoryflow signal Qr and provides as an output a metric of the extent to whichsnoring is present.

Preferably the algorithm 4326 comprises the step of determining theintensity of the flow signal in the range of 30-300 Hz. Furtherpreferably, algorithm 4326 comprises a step of filtering the respiratoryflow signal Qr to reduce background noise, e.g. the sound of airflow inthe system from the blower.

5.4.2.2.7 Determination of Airway Patency 4327

In one form of the present technology, the central controller 4230executes one or more algorithms 4327 for the determination of airwaypatency.

In one form, airway patency algorithm 4327 receives as an input arespiratory flow signal Qr, and determines the power of the signal inthe frequency range of about 0.75 Hz and about 3 Hz. The presence of apeak in this frequency range is taken to indicate an open airway. Theabsence of a peak is taken to be an indication of a closed airway.

In one form, the frequency range within which the peak is sought is thefrequency of a small forced oscillation in the treatment pressure Pt. Inone implementation, the forced oscillation is of frequency 2 Hz withamplitude about 1 cmH20.

In one form, airway patency algorithm 4327 receives as an input arespiratory flow signal Qr, and determines the presence or absence of acardiogenic signal. The absence of a cardiogenic signal is taken to bean indication of a closed airway.

5.4.2.2.8 Determination of Therapy Parameter Determination 4328

In one form of the present technology, the central controller 4230executes one or more therapy parameter determination algorithms 4328 forthe determination of a target treatment pressure Pt to be delivered bythe RPT device 4000.

Preferably the therapy parameter determination algorithm 4328 receivesas an input one of more of the following:

-   -   A measure of respiratory phase;    -   A waveform;    -   A measure of ventilation;    -   A measure of inspiratory flow limitation;    -   A measure of the presence of apnea and/or hypopnea;    -   A measure of the presence of snore; and    -   A measure of the patency of the airway.

The therapy parameter determination algorithm 4328 determines thetreatment pressure Pt as a function of indices or measures of one ormore of flow limitation, apnea, hypopnea, patency, and snore. In oneimplementation, these measures are determined on a single breath basis,rather than on an aggregation of several previous breaths.

FIG. 4 e is a flow chart illustrating a method 4500 carried out by thecentral controller 4230 as one implementation of the algorithm 4328. Themethod 4500 starts at step 4520, at which the central controller 4230compares the measure of the presence of apnea/hypopnea with a firstthreshold, and determines whether the measure of the presence ofapnea/hypopnea has exceeded the first threshold for a predeterminedperiod of time, indicating an apnea/hypopnea is occurring. If so, themethod 4500 proceeds to step 4540; otherwise, the method 4500 proceedsto step 4530. At step 4540, the central controller 4230 compares themeasure of airway patency with a second threshold. If the measure ofairway patency exceeds the second threshold, indicating the airway ispatent, the detected apnea/hypopnea is deemed central, and the method4500 proceeds to step 4560; otherwise, the apnea/hypopnea is deemedobstructive, and the method 4500 proceeds to step 4550.

At step 4530, the central controller 4230 compares the measure of flowlimitation with a third threshold. If the measure of flow limitationexceeds the third threshold, indicating inspiratory flow is limited, themethod 4500 proceeds to step 4550; otherwise, the method 4500 proceedsto step 4560.

At step 4550, the central controller 4230 increases the treatmentpressure Pt by a predetermined pressure increment ΔP, provided theincreased treatment pressure Pt would not exceed an upper limit Pmax. Inone implementation, the predetermined pressure increment AP and upperlimit Pmax are 1 cmH20 and 20 cmH20 respectively. The method 4500 thenreturns to step 4520.

At step 4560, the central controller 4230 decreases the treatmentpressure Pt by a decrement, provided the decreased treatment pressure Ptwould not fall below a lower limit Pmin. The method 4500 then returns tostep 4520. In one implementation, the decrement is proportional to thevalue of Pt-Pmin, so that the decrease in Pt to the lower limit Pmin inthe absence of any detected events is exponential. Alternatively, thedecrement in Pt could be predetermined, so the decrease in Pt to thelower limit Pmin in the absence of any detected events is linear.

5.4.2.3 Control Module 4330

A control module 4330 in accordance with one aspect of the presenttechnology receives as an input a target treatment pressure Pt, andcontrols a pressure generator 4140 to deliver that pressure.

A control module 4330 in accordance with one aspect of the presenttechnology receives as an input an EPAP pressure and an IPAP pressure,and controls a pressure generator 4140 to deliver those respectivepressures.

5.4.2.4 Detection of Fault Conditions 4340

In one form of the present technology, the central controller 4230executes one or more methods for the detection of fault conditions.Preferably the fault conditions detected by the one or more methodsincludes at least one of the following:

-   -   Power failure (no power, or insufficient power)    -   Transducer fault detection    -   Failure to detect the presence of a component    -   Operating parameters outside recommended ranges (e.g. pressure,        flow, temperature, PaO2)    -   Failure of a test alarm to generate a detectable alarm signal.    -   Upon detection of the fault condition, the corresponding        algorithm signals the presence of the fault by one or more of        the following:    -   Initiation of an audible, visual &/or kinetic (e.g. vibrating)        alarm    -   Sending a message to an external device    -   Logging of the incident

5.5 HUMIDIFIER 5000 5.5.1 Humidifier Overview

In one form of the present technology there is provided a humidifier5000 to change the absolute humidity of air for delivery to a patientrelative to ambient air. Typically, the humidifier 5000 is used toincrease the absolute humidity and increase the temperature of the flowof air relative to ambient air before delivery to the patient's airways.

There are a number of performance requirements and/or designrequirements that may be relevant to a humidifier. Some knownperformance requirements and/or design requirements in relation tohumidifier design may include: reduction of a volume and/or a footprintof the humidifier (e.g. for bedside placement), ability to providehumidification for an entire therapy session, efficient use of the watersupply, requirement to couple to the respiratory apparatus, minimisationof pressure drop for the flow of air through the humidifier, and/orrequirement to maintain a positive pressure at the entrance of thepatient's airways (e.g. therefore a requirement to maintain a positivepressure in the humidifier). It is one of the aims of the presenttechnology to address, or improve, at least some of the aboveperformance requirements and/or design requirements.

A simplified representation of a humidifier 5000 is shown in FIG. Sa. Inone form, a humidifier 5000 may comprise a humidifier reservoir 5110, aheating element 5240 and one or more sensors 5270. The humidifier 5000may be configured to receive a flow of air from a pressure generator4140 via an air circuit 4170, and deliver a flow of humidified air to apatient interface 3000 (not shown in FIG. 5 a), for example via a heatedair circuit 4171.

A simplified schematic of a humidifier 5000 according to an example ofthe present technology is shown in FIG. 5 b. The humidifier 5000 maycomprise one or more controllers 5250 such as a heated air circuitcontroller 5254, a heating element controller 5252 or a centralhumidifier controller 5251, which may be discrete controllers or onecontroller performing multiple functions. The controller(s) 5250 may bein electrical communication with one or more of: one or more sensors5270, input devices 4220, output devices 4290, heated air circuit 4171and a heating element 5240 as shown in FIG. 5 b.

5.5.2 Humidifier Mechanical Components 5100 5.5.2.1 Water Reservoir Dock5130

As shown in FIGS. 13 to 16, a humidifier 5000 may comprise a waterreservoir dock 5130 to receive a water reservoir 5110. As shown in FIG.14, the water reservoir dock 5130 may comprise a cavity 5160 formedtherein to receive the water reservoir 5110. In one form, the waterreservoir dock 5130 may be integrated with the humidifier 5000 as shownin FIGS. 13 to 16. The water reservoir dock 5130 may also connect thewater reservoir 5110 to the pneumatic path. In this arrangement, thereservoir dock 5130 comprises a dock air outlet 5168 to deliver a flowof air to a water reservoir 5110, a dock air inlet 5170 to receive theflow of air that has been humidified in the water reservoir 5110, and ahumidifier outlet 5172 to transfer the flow of humidified air to the aircircuit 4170. The cavity 5160 may include a top portion configured tocover at least a portion of the lid of the reservoir 5110 and a bottomportion including the heater plate 5120.

It should be understood that the reservoir dock 5130 may be providedseparately to a humidifier 5000 in an alternate arrangement. In such anarrangement, additional interfaces may be used to connect the reservoirdock 5130 to the humidifier 5000.

In another arrangement, a water reservoir dock 5130 may comprise anopening in a substantially horizontal plane, so that the water reservoir5110 may be inserted from above or below the water reservoir dock 5130.

5.5.2.2 Water Reservoir 5110

FIGS. 9 to 12 show one form of a water reservoir 5110, which comprises areservoir base 5112, a reservoir lid 5114, and an intermediate portion5202 including a compliant portion 5116. The reservoir 5110 isconfigured to hold a given, maximum volume of liquid (e.g. water),typically several hundred millilitres, e.g. 300 millilitres (ml), 325ml, 350 ml or 400 ml, although it is to be understood that other volumesof liquid may be utilised such as 100 ml, 200 ml, 250 ml, 500 ml or moreor less. In one form, the reservoir 5110 may comprise a cavity formed bya plurality of walls to hold the given, maximum volume of liquid asshown in FIGS. 11 and 12.

According to one aspect, the water reservoir 5110 is configured to addhumidity to a flow of air from the RPT device 4000. The water reservoir5110 may be configured to do so by encouraging the flow of air to travelin a tortuous path through the reservoir 5110. The reservoir 5110 isalso configured to discourage egress of liquid therefrom, such as whenthe reservoir 5110 is displaced and/or rotated from its normal, workingorientation, liquid will not leak through any apertures and/or inbetween its sub-components. As the flow of air to be humidified by thehumidifier 5000 is typically pressurised, the reservoir 5110 may also beconfigured to prevent losses in pneumatic pressure through leak and/orflow impedance.

The water reservoir 5110 may comprise an inlet 5118 for receiving theflow of air into the reservoir 5110, and an outlet 5122 for delivering aflow of air from the reservoir 5110. In one form, the reservoir 5110 mayinclude to an inlet tube 5124 and/or an outlet tube 5126 (e.g., seeFIGS. 10 and 12). In one configuration the inlet 5118 and inlet tube5124 are integrally formed as one inlet component and the outlet 5122and the outlet tube 5126 are integrally formed as one outlet component(see FIGS. 10-12, 22-29 and 47 a-52 b). In other configurations theinlet tube 5124 and/or the outlet tube 5126 may be separate tubes thatare coupled to the inlet 5118 and/or the outlet 5122 respectively (seeFIGS. 41 a to 46). The water reservoir 5110 is configured to increasethe humidity of the flow of air as it flows through the reservoir 5110.

5.5.2.2.1 Water Reservoir Lid 5114

In one form, the water reservoir lid 5114 is pivotably connected to thebase 5112 by hinges 5158 to allow the reservoir 5110 to be convertedbetween an open configuration, as shown in FIG. 11, and a closedconfiguration, as shown in FIG. 9 and FIG. 10. When the water reservoir5110 is in its closed configuration, the compliant portion 5116 is putinto sealing engagement between the base 5112 and the lid 5114 to sealthe base 5112 and the lid 5114 and prevent egress of water from thereservoir 5110. The hinges 5158 may couple to complementary hinge recessportions 5159 (see FIG. 12) located in the reservoir base 5112. In oneform, the lid 5114 may be constructed from a bio-compatible material,such as a plastic or thermoplastic polymer, for example, acrylonitrilebutadiene styrene (ABS) or polycarbonate material.

Another aspect of the present technology relates to the operation of thepivoting action in the lid 5114 in relation to the base 5112. As the lid5114 rotates about the hinges 5158, a range of rotation may be definedas shown in FIG. 51 a and FIG. 51 b. In one form, two ends of the rangeof rotation may be defined by closure of the lid 5114 with respect tothe base 5112, where one of the two ends may be a fully open positiondefined by a rotation guide 5220, which may interfere with a rotationstop 5222 at the fully open position.

According to another aspect, the lid 5114 may configured so that when auser attempts to open the lid 5114 further than the rotation stop 5222and the rotation guide 5220, the lid 5114 would disconnect from the base5112. As shown in FIG. 51 b and FIG. 52 b, at the fully open positionthe rotation guide 5220 may be in contact with the rotation stop 5222.In this form, attempts to further open the lid 5114 with respect to thebase 5112 would cause the rotation stop 5222 to act as a pivot of acantilever, and cause the lid 5114 to separate from the base 5112 at thehinges 5158, whereby damage to the reservoir 5110, for example fromapplication of excessive force thereto, may be avoided. In one form, thehinges 5158 may be configured to allow disconnection more easily at oneorientation of the lid 5114 with respect to the base 5112 (e.g. then thereservoir 5110 is in the fully open position) than at anotherorientation. This may be achieved by, for example, introduction of ataper to the hinges 5158 on the lid 5114 as shown in FIGS. 47 a and 47b.

5.5.2.2.2.2 Compliant Portion 5116

In one form, when the water reservoir 5110 is in use, the compliantportion 5116 may act as a seal between the reservoir base 5112 and thereservoir lid 5114. The compliant portion 5116 may also perform otherfunctions, such as to improve thermal contact between the reservoir 5110and the heater plate 5120, as will be described in further detail below.

The compliant portion 5116 may be provided as part of the reservoir lid5114 or as part of the reservoir base 5112, or independently of both,for example as part of an intermediate portion 5202. The compliantportion 5116 may be engaged with the reservoir lid 5114 or the reservoirbase 5112 by any number of means including, and not limited to,ultrasonic welding, friction fitting, gluing or by using an intermediatecomponent. The intermediate portion 5202 may include the compliantportion 5116 and a carrier 5117 (as shown in FIG. 12).

The compliant portion 5116 preferably includes a sufficiently resilientconstruction so as to be able to resist forces and/or pressuresgenerated in the reservoir 5110, such as those generated by the user,the reservoir dock 5130 and/or the flow of air flowing through thereservoir 5110. The compliant portion 5116 is also preferably compliantto be able couple to the lid 5114 and/or the base 5112, and conform toits shape. In one form, the carrier 5117 of the intermediate portion maybe constructed from a nylon material of approximately 2 mm thickness(such as 1 mm, 1.5 mm, 2.5 mm or 3 mm), and a silicone material may beused to overmould onto the carrier 5117 to form the compliant portion ofthe intermediate portion 5202.

In some arrangements, the compliant portion 5116 may couple to the lid5114 and/or the base 5112, and the base 5112 and/or the lid 5114 may beformed as two separate parts that are able to be assembled with thecompliant portion 5116 coupled therebetween.

In an alternative arrangement, the compliant portion 5116 may be locatedwithin a wall of the reservoir base 5112 and/or a wall of the reservoirlid 5114, for example integrally by overmoulding or as a separatecomponent connected as a sub-assembly. In such an arrangement thecompliant portion would not be located between the reservoir base 5112and the reservoir lid 5114 but within the reservoir base 5112 and/or thereservoir lid 5114. There may be more than one compliant portion 5116 orthe compliant portion may be formed in multiple parts to provide morecompliance in movement of the reservoir 5110.

5.5.2.2.3 Water Reservoir Bare 5112

According to one arrangement, the reservoir base 5112 comprises aconductive portion (such as the base conductor plate 5152, e.g., seeFIG. 12) configured to thermally couple with a heater plate 5120 of thehumidifier 5000. The conductive portion improves efficiency of heattransfer from the heater plate 5120 to the volume of liquid in thereservoir 5110. All or a part of the base conductor plate 5152 may bemade of a heat conducting material such as aluminium (e.g. approximately2 mm thick, such as 1 mm, 1.5 mm, 2.5 mm or 3 mm) or another heatconducting material such as metal. In some cases, suitable heatconductivity may be achieved with less conductive materials of suitablethickness.

The reservoir base 5112 may also be configured as a receptacle to retainthe given, maximum volume of liquid that the reservoir 5110 isconfigured to hold. In one form, the base 5112 may comprise furtherfeatures such as an overfill prevention feature as will be described infurther detail below. In one form, the reservoir base 5112 may alsocomprise a base upper body 5146 and a base bottom plate 5148, whichtogether with the base conductor plate 5152 may form a receptacle, e.g.,see FIG. 12.

The base upper body 5146 and/or the base bottom plate 5148 may beconstructed from a bio-compatible material suitable for retaining thevolume of liquid, such as a plastic or thermoplastic polymer, forexample, ABS or polycarbonate material. The base conductor plate 5152may comprise of a sealing element 5150, e.g., see FIG. 12, which may beintegrated to, and/or sealingly connected to both the base upper body5146 and the base bottom plate 5148 to prevent egress of water from thewater reservoir 5110, particularly from the base 5112. For example, thesealing element 5150 may be overmoulded onto the base conductor plate5152, and the resulting component may be secured between the base upperbody 5146 and the base bottom plate 5148.

In one form as shown in FIG. 12, the base 5112 may comprise a base upperbody 5146, a base bottom plate 5148, and a base conductor plate 5152.However, it should be appreciated that the reservoir base 5112 may beconstructed in any number of parts. The reservoir base 5112 may beconstructed as a single part made of, for example, aluminium or anotherheat conducting material such as metal. In another arrangement, thereservoir base 5112 may be constructed in two parts, for examplecomprising a lower component and an upper component. In such anarrangement, the lower component may be constructed from a heatconducted material and perform the roles of the base conductor plate5152, sealing element 5150 and base bottom plate 5148, and the uppercomponent may be equivalent to the base upper body 5146, and beconstructed of a polycarbonate material.

In one form, the reservoir base 5112 may further comprise an inner lip5224 and/or an outer lip 5226, for example as shown in FIG. 53 and FIG.54. According to one aspect, the inner lip 5224 and/or outer lip 5226may prevent egress of liquid from the reservoir 5110 through theinterface between an intermediate portion 5202 (e.g. the compliantportion 5116) and the base 5112, for example when the intermediateportion 5202 is compressed, or when the intermediate portion 5202 isunder vibration.

5.5.2.2.4 Water Reservoir-to-Humidifier Connection

When in use, the water reservoir 5110 receives the flow of air forexample output by the RPT device 4000. In one form, the water reservoir5110 is removably coupled with the humidifier 5000 as shown in FIGS. 13to 16 by inserting the water reservoir into the water reservoir dock5130, for example by sliding. The inlet 5118 of the water reservoir 5110is configured to receive the flow of air that is output by the RPTdevice 4000, and to direct the flow of air into the water reservoir5110. Humidity (i.e. water vapour) is added to the flow of air as theair travels through the reservoir 5110, and the humidified flow of airexits the reservoir 5110 through the outlet tube 5126 and to thereservoir outlet 5122. The reservoir outlet 5122 is connectable to anair circuit 4170 to deliver the flow of humidified air to the patient1000.

The double-ended arrows in FIG. 14 and FIG. 16 show the direction ofrelative motion, i.e. generally horizontal movement, between thehumidifier 5000 and the water reservoir 5110 in connection anddisconnection with each other in this arrangement. However, the waterreservoir 5110 may be coupled to the humidifier 5000 by other methodssuch as insertion in a generally vertical direction, connection by oneor more intermediate components (e.g. tubes) or being integrally formedwith a humidifier.

In an alternative arrangement, not shown, the water reservoir 5110 maybe inserted into the dock cavity 5160 from a vertical direction ratherthan using a sliding motion. In such an arrangement the dock cavity ofthe humidifier 5000 may comprise a moveable cover portion, such as a lidor top portion, which is at least partially opened to allow insertion ofthe water reservoir 5110 and closed following insertion to secure thewater reservoir 5110 within the dock cavity 5160.

In the illustrated arrangement (see FIG. 16) the reservoir outlet 5122is connectable to the reservoir dock air inlet 5170, through which thehumidified flow of air travels to the humidifier outlet 5172. Thehumidifier outlet 5172 is connectable to the air circuit 4170 asindicated in FIG. 13 by the double-ended dotted arrow (see FIG. 13). Anadvantage of such an arrangement is that the humidifier reservoir 5110can be removed from the dock cavity 5160 while the air circuit 4170remains attached to the humidifier outlet 5172. Thus the insertion andremoval of the humidifier reservoir 5110 is independent of theconnection of the air circuit 4170. A further advantage is that thehumidifier reservoir 5110 must be removed from the reservoir dock 5130to fill the humidifier reservoir 5110 with liquid. In this form, neitherof the inlet 5118 and the outlet 5122 of the reservoir 5110 are exposedwhile the reservoir 5110 is inserted in the humidifier 5000 in anoperating configuration, while the reservoir 5110 itself remainsaccessible to the patient 1000, for example to allow easy removal fromthe humidifier 5000. This arrangement may reduce the likelihood of theuser over-filling the water reservoir 5110 over the given, maximumvolume of liquid, as the humidifier reservoir 5110 incorporates featuresto prevent over-filling as described further below. Still further, asthe user is encouraged to remove the water reservoir 5110 to fill thereservoir 5110 with liquid, the likelihood of spillage of water onto, orinto, the humidifier 5000 and/or the RPT device 4000 is reduced.

As shown in FIG. 16, first and second dock seals 5132, 5134 may beprovided to help seal the connection between the reservoir inlet 5118and the dock 5130 and the connection between the reservoir outlet 5122and the dock 5130.

In the arrangement shown in FIGS. 15 and 16, the water reservoir 5110 isconnected with the humidifier 5000 by placing the water reservoir 5110in the water reservoir dock 5130. In this arrangement, the heights andshapes of the dock internal cavity 5160 and the water reservoir 5110 aresuch that to engage the water reservoir 5110 with the water reservoirdock 5130 the compliant portion 5116 is compressed, for example bybetween about 1 mm and about 5 mm, for example by about 2 mm, about 3 mmor about 4 mm. Thus, the shape of the portion of the water reservoir5110 that is inserted into the dock 5130 is complementary to the shapeof the dock cavity 5160 and the height of the water reservoir 5110 whencompliant portion 5116 is compressed is slightly less than the height ofthe dock cavity 5160 to enable the insertion of the water reservoir 5110into the dock cavity 5160.

The compliant portion 5116 may be constructed with a cross-section shapesuch as one shown in FIG. 39. A compressive force is required tosufficiently compress the compliant portion 5116 and allow relativemovement (i.e. sliding) between the water reservoir 5110 and the waterreservoir dock 5130. For example a compression force as measured at thehandle recesses 5154, 5156 of between about 10 N and about 30 N, orabout 20 N, or some other compression force is required to allowinsertion of the water reservoir 5110 into the dock cavity 5160. Thevertical gap achieved between the water reservoir 5110 and the dockinternal cavity 5160 during insertion (or removal) may be between about1 mm and about 5 mm, for example about 2 mm, 3 mm or 4 mm, when thiscompressive force is applied at the handle recesses and the waterreservoir 5110 is inserted into the reservoir dock 5130. The waterreservoir 5110 and the reservoir dock 5130 may be arranged so that theamount of compression in the compliant portion 5116 is reduced once thewater reservoir 5110 is connected with the reservoir dock 5130 and thepatient 1000 is no longer applying a compressive force. The reduction incompression may be between about 0.5 mm and about 2.5 mm, for exampleabout 1 mm, 1.5 mm or 2 mm.

The compliant portion 5116 may be constructed from an elastomericmaterial such as silicone, thermoplastic elastomer (TPE), TPE polyester,TPE polyurethane or natural rubber. In choosing the material to be usedfor the compliant portion 5116 it may be advantageous to choose one thatdoes not experience mechanical relaxation across the range of storageand operational temperatures that the compliant portion 5116 may beexposed to. One example of a material for the compliant portion 5116which meets these requirements may be silicone.

A reservoir latch 5186 may be provided on the water reservoir 5110, asshown in FIG. 40, so that when the reservoir latch 5186 is engaged, itsecures the reservoir lid 5114 and reservoir base 5112 together. Thelatch 5186 may prevent the reservoir lid 5114 and the reservoir base5112 from separating and maintain the compliant portion 5116 in sealingengagement between the lid 5114 and the base 5112, for example bycompression. In one form, the latch 5186 may be configured to restrictrelative movement of the lid 5114 in relation to the base 5112 in onedirection only, thus allow further compression of the compliant portion5116 while preventing separation of the lid 5114 and the base 5112. Thismay allow insertion of the water reservoir 5110 into the reservoir dock5130, and/or allow the compliant portion 5116 to assist thermalengagement between the reservoir 5110 and the heater plate 5120 asdescribed elsewhere in this disclosure.

5.5.2.2.5 Reservoir Handles 5154, 5156

FIGS. 13 to 16 show an upper handle 5154 that is located on thereservoir lid 5114, and a lower handle 5156 that is located on thereservoir base 5112. These handles are intended to assist the patient(or user) 1000 to grip and hold the water reservoir 5110. In the shownarrangement, the handles 5154, 5156 are located away from the hinges5158 such that, by holding the reservoir 5110 by the handles 5154, 5156,the patient 1000 imparts forces onto the reservoir 5110 compressing thecompliant portion 5116, which pushes the lid 5114 and the base 5112towards each other. A compression force may also help maintain thecompliant portion 5116 in sealing engagement between the reservoir base5112 and the reservoir lid 5114, such as during transport to/fromre-filling the reservoir 5110 with liquid. It is to be understood thatthe handles 5154 and 5156 may be placed on other components or areas ofthe water reservoir 5110.

A handle grip 5166 may be provided on a surface of either or both of thehandles 5154, 5156 as shown in FIG. 14. The handle grip 5166 may beconstructed to assist the patient 1000 to hold the reservoir 5110, suchas by being made from a higher friction material, made in a higherfriction texture and/or made into an easier-to hold shape than thesurrounding areas of the reservoir 5110. For example, the handle grip5166 may be constructed from an elastomeric material such as siliconewhereas the water reservoir 5110 may primarily be constructed from apolycarbonate material. Additionally, or alternatively, the handle grip5166 may comprise geometric features such as ribs or ridges to reduce achance of slippage between fingers and the handles 5154, 5156.

5.5.2.2.6 Air Flow Path

In one form of the present technology the flow of air is guided totravel through the reservoir 5110 in a tortuous path between the inlet5118 and the outlet 5122. This prevents any ‘short-circuiting’ of theflow of air, which may lead to inadequate humidity in the flow of airwhich is delivered to the patient 1000.

FIGS. 17 a to 17 c, 18 a to 18 c, and 19 a to 19 c show an exemplarypath of the flow of air through the reservoir 5110 as it enters throughthe inlet 5118 and exits through the outlet 5122. The figures arearranged chronologically in three distinct orthogonal views per figureto visually demonstrate the exemplary flow path. In this arrangement theflow of air received through the inlet 5118 passes through the inlettube 5124 (FIGS. 17 a to 17 c), into the internal volume of the waterreservoir 5110 (FIGS. 18 a to 18 c). The flow of air then passes throughthe outlet tube 5126 to exit the water reservoir 5110 at the outlet 5122(FIGS. 19 a to 19 c) as humidified air. FIGS. 17 a to 17 c, 18 a to 18c, and 19 a to 19 c show the reservoir 5110 with the lid 5114 and thebase 5112 in exploded view orientation for clarity, and any flow of airthat occurs in the internal volume of the reservoir 5110 is shown indotted lines. The dotted arrows shown indicate the general direction ofthe exemplary flow of air, although it is noted that the nature of airflow means that any air flow path includes swirling (e.g. turbulence) ofthe air rather than a straight and direct air flow path.

In some forms of the present technology, the reservoir 5110 may compriseflow elements, such as a baffle 5192 shown in rig. 42, configured toincrease the length of the tortuous flow path and/or to prevent ingressof water into the inlet tube 5124 and/or the outlet tube 5126. Forinstance, the reservoir 5110 may comprise a deflector portion 5198 asshown in FIGS. 41 a, 41 b, 42, 43 a, 43 b, and 44, or a deflectorportion 5198 and a flow director 5195 as shown in FIGS. 47 a and 47 b.In some arrangements, the baffle 5192 may further comprise a locatingportion 5196 as will be described in further detail below.

In the arrangement shown in FIGS. 41 a, 41 b, 42, 43 a, 43 b, and 44,the deflector portion 5198 is configured to prevent the flow of air fromentering the outlet tube 5126 immediately after exiting the inlet tube5124 through the inlet tube inner end (or inner tube outlet) 5125 (i.e.short-circuiting). In some of the arrangements (e.g., as illustrated inFIGS. 41 a, 41 b, 42, 43 a, 43 b and 44) the outlet tube 5126 may beformed as part of the intermediate portion 5202 and connect to theoutlet 5122 of the reservoir when assembled with the lid portion 5114.When the intermediate portion 5202 and the lid portion 5114 areassembled together as seen in FIG. 41 a, the deflector portion 5198 maybe located close to the inlet tube inner end 5125, such as by abuttingit. In this arrangement, the deflector portion 5198 forms a coverbetween the inlet tube inner end 5125 and a base of the outlet tubeinner end 5127. This cover may be further advantageous in that it forcesthe flow of air to travel in a channel created by the cover and thevolume of water in the reservoir 5110 for improved humidity pickup.

In the arrangement shown in FIGS. 47 a and 47 b, the reservoir 5110includes a flow director 5195 as well as a deflector portion 5198. Thedeflector portion 5198 is configured to prevent short-circuiting of theflow of air, and the flow director 5195 is further configured to directthe flow of air that exits the inlet tube 5124 in a directionapproximately parallel with the volume of liquid in the reservoir 5110.This may ameliorate occurrence of ‘spitting’, which can occur when theflow of air exits the inlet tube 5124 in a direction normal to thesurface of the volume of liquid.

As shown in FIGS. 22 and 23, the reservoir 5110 may include an end wall5128 that is near and opposed to the inlet tube inner end 5125. Theinner end wall 5128 of the reservoir 5110 directs air exiting the inlettube 5124 to flow across the water surface before it reaches an outlettube inner end 5127 and flows out of the outlet 5122 through the outlettube 5126. FIGS. 24 to 27 show examples of other arrangements of flowelements, wherein the reservoir 5110 may include a turning vane 5136which is placed near the interior end 5125 of the inlet tube 5124. Theturning vane 5136 may be integrally formed as an extension of the inlettube 5124 as shown in FIGS. 26 and 27, or the turning vane 5136 may be aseparate component located adjacent to or coupled with the inlet tube5124. The turning vane 5136 may also be profiled as shown in FIGS. 26and 27.

The path of the flow of air demonstrated in FIGS. 17 a to 17 c, 18 a to18 c, and 19 a to 19 c is exemplary only, and is aimed to demonstrateone of many paths that the flow of air may traverse through the waterreservoir 5110, namely that it enters the water reservoir 5110 throughthe inlet 5118 and exits through the outlet 5122 after experiencing somedegree of swirling within the volume of the water reservoir 5110. Aperson skilled in the art would understand that the panicles ormolecules that form the flow of air may not follow a single path withinthe water reservoir 5110 due to a number of factors, including, forexample, localised turbulence (eddies) or pressure gradients within thewater reservoir 5110. As a result, the cumulative path of the flow ofair may comprise any number of paths wherein it experiences variousdegrees of ‘swirling’ within the water reservoir 5110 prior to exitingvia the outlet tube 5126 at the outlet 5122. It is also possible thatsome small portion of the flow of air may escape the water reservoir5110 as a leak.

5.5.2.2.7 Thermal Contact/Engagement

According to one aspect of this technology, the water reservoir 5110 andthe heater plate 5120 of the humidifier are in thermal contact, orthermal engagement, as described above. A degree of thermal contact, forexample measured in thermal conductivity or thermal contact resistance,between two components may vary according to a number of parameters.

In the prior art, additional components have been used to improvethermal contact between a water reservoir and a heater plate byincreasing the contact pressure therebetween. One example is the use ofspring elements, which are used to connect the heater plate to thehumidifier body, as described in U.S. Pat. No. 4,203,027, therebypushing the heater plate towards the water reservoir. Another example isa humidifier with a lid wherein a compressible elastomer seal isprovided on the lid, as described in WO2010031126. In this example, whenthe lid is in its closed position the seal engages against the waterreservoir and pushes it against the heater plate.

5.5.2.2.7.1 Pre-Compression for Improved Thermal Contact

In the present technology, pre-compression of the water reservoir 5110,for example in engagement with the water reservoir dock 5130, may beused to help improve thermal contact between the reservoir 5110 and theheater plate 5120.

In one arrangement, the water reservoir 5110 may be configured so thatin its operating configuration, such as when it is placed in the waterreservoir dock 5130, the compliant portion 5116 is compressed asdescribed above. The reservoir 5110 and the reservoir dock 5130 may befurther configured so that a reaction force to the compression of thecompliant portion 5116 pushes the base 5112 of the water reservoir 5110against the heater plate 5120 to improve the thermal contacttherebetween.

Thus, the compliant portion 5116 may act as a spring that is biased topush the reservoir base 5112 and/or the reservoir lid 5114 in adirection perpendicular to the heater plate 5120. As the reservoir 5110is secured externally, such as confined within the reservoir dock 5130,the compression of the compliant portion 5116 is reacted by a force thatencourages improved thermal engagement with the heater plate 5120. FIG.20 illustrates this effect by indicating the distributed forces orpressures that are applied to the lid 5114, compliant portion 5116 andthe base 5112 by the arrows shown.

The force required for compression of the compliant portion 5116 whenthe water reservoir 5110 is connected with the humidifier 5000 ispreferably in the same direction as the normal to a surface of theconductive portion. The direction may be also preferably in the samedirection as the direction of thermal engagement. This force is reactedby the water reservoir dock 5130 at its contacting points and/orsurfaces, thereby pushing the base 5112 of the water reservoir 5110 andthe heater plate 5120 together.

The magnitude of compression force may be between about 5 N and about 15N when measured at the heater plate 5120 when the water reservoir 5110is placed in the water reservoir dock 5130. However, it should beunderstood that different configurations of the water reservoir 5110 mayrequire different magnitudes of compression force. The magnitude of thisforce may be altered by modifying the design of any or all of thecompliant portion 5116, the lid 5114, the base 5112, or the reservoirdock 5130. For instance, if the compliant portion 5116 was constructedof a material with higher Young's modulus, it would correspondinglyincrease the magnitude of the force. It should be noted that FIG. 20only shows forces and pressures in the vertical direction.

In some cases, the amount of compression of the compliant portion 5116in the reservoir 5110 may be used to vary a level of thermal engagementbetween the conductive portion and the heater plate 5120.

5.5.2.2.7.2 Use of Pressurised Air for Improved Thermal Contact

According to another aspect, when the water reservoir 5110 is connectedwith the humidifier 5000, the flow of air received from the RPT devicemay pressurise a chamber such as the interior of the reservoir 5110. Thepressurisation of the chamber may be used to increase a level of thermalengagement (i.e. thermal contact) between the reservoir 5110 and theheater plate 5120. The reservoir 5110 may be further configured so thatby varying the level of pressure in the chamber may vary the level ofthermal contact between the reservoir 5110 and the heater plate 5120.

In one form, the compliant portion 5116 may be configured to beexpandable in the direction of thermal contact, and the reservoir 5110may be confined by the reservoir dock 5130 in the same direction. Inthis form, the internal pressure pushes the base 5112 of the waterreservoir 5110 against the heater plate 5120 to improve the level ofthermal engagement between the heater plate 5120 and the base 5112.

FIG. 21 illustrates this effect by indicating the distributed forces orpressures that are applied to the lid 5114 and the base 5112 by thearrows shown. FIG. 21 shows forces and pressures in the verticaldirection only, as in this form the thermal engagement occurs in thevertical direction. The presence of above-atmospheric pressure withinthe water reservoir 5110 results in forces in the direction of thermalengagement, and is reacted by the water reservoir dock 5130 at itscontacting surfaces, thereby pushing the base 5112 of the waterreservoir 5110 and the heater plate 5120 together in the direction ofthermal engagement. The magnitude of this force may be between about 5 Nand about 15 N when measured at the heater plate 5120 at 20 cm H₂O ofpressure.

It should be understood that different configurations of the waterreservoir 5110 may require different magnitudes of force, which may beachieved by varying the surface area that the pressure acts on, or theeffective pressure that acts on the surface. Such changes may beachieved, for example, by a pressure regulating valve.

In another arrangement, substantially the same effects as thosedescribed above may be achieved with a non-opening compliant portion ofa water reservoir 5110. The water reservoir 5110 and the reservoir dock5130 may be arranged so that elasticity or flexibility is provided by anelastomeric material or a joint that allows freedom of movement (e.g. asliding connection, or a concertina section of pliable plastic or aflexible portion in the water reservoir) in the direction of the heattransfer. In this configuration the lid 5114 and the base 5112 may beunconstrained relative to each other in the direction of thermalcontact. The reservoir 5110 may then be constrained in the direction ofthe heat transfer in another manner (e.g. by a water reservoir dock or asimilar housing) to create a force that reacts to balance the pressurecreated in the interior of the reservoir 5110 by the pressurized flow ofair, wherein some of the reaction force may occur at the heater plate5120 to improve thermal contact. In such arrangements, another openingto re-fill the water reservoir 5110 may be introduced on the reservoir5110, such as on the lid 5114, and it may comprise a separate sealaround such opening.

FIG. 34 shows an example of such an arrangement, including a base 5174,a top 5176, a compliant portion 5178 and a re-filling cap 5180. Thebase, the top and the compliant portion may be affixed together inanother arrangement, wherein re-filling of the reservoir would beaccommodated by the re-filling cap 5180. The re-filling cap 5180 may beplaced such that, when the humidifier reservoir 5110 is engaged with thereservoir dock 5130, the re-filling cap 5180 is not accessible. Such anarrangement may preserve the advantage described above, namely that thereservoir 5110 is not able to be re-filled while it is engaged with thereservoir dock 5130. Furthermore, the compliant portion 5178 may bereplaced by any mechanism known in the art that is able to accommodate achange in vertical length within a reservoir.

In yet another alternate arrangement, the flow of air may be used toimprove the level of thermal contact between the humidifier reservoir5110 and the heater plate 5120 by pressurisation or inflation of asecondary component. The secondary component may be a chamber, body orsurface that acts on the humidifier reservoir 5110, which in turn pushesthe water reservoir 5110 and the heater plate 5120 together in thedirection of thermal engagement. Similarly, the secondary component mayact upon the heater plate 5120 to push the heater plate 5120 and waterreservoir 5110 together in the direction of thermal engagement.

The secondary component may be arranged externally to the reservoir 5110and/or the heater plate 5120. Furthermore, the secondary component maybe configured to vary the area in contact with the reservoir 5110 and/orthe heater plate 5120, to further profile the change to thermal contactas pressure of the flow of air changes.

In an alternate arrangement, the water reservoir dock 5130 may include aretaining mechanism (for example, a lid that closes around the waterreservoir 5110 to hold the water reservoir 5110 in its intendedposition. In such an arrangement, a reservoir dock lid may be configuredto compress and/or confine the compliant portion 5116 in order toimprove the level of thermal contact.

The level of thermal contact may also be further improved using a springloaded or sprung heater plate as is known in the prior art. The heaterplate may be constructed with a convex or domed shape towards thehumidifier reservoir 5110 so that when the humidifier 5110 is engagedwith the reservoir dock 5130 the convex heater plate is flattened, whichgenerates a clamping force pushing the heater plate 5120 to the waterreservoir 5110. Similarly, the conductor plate 5152 of the waterreservoir 5110 may be domed or convex shaped and be configured to beflattened towards to the heater plate when the water reservoir 5110 isengaged in the dock cavity 5160 of the humidifier 5000.

Any one of the above means of improving thermal contact may be usedindependently of each other, or in any combination thereof, including incombination with any prior art means of achieving or improving thermalengagement between the humidifier reservoir and the heater plate.

5.5.2.2.8 Reservoir Inlet/Outlet

As described above, the reservoir inlet 5118 is configured to receivethe flow of air into the reservoir 5110, and the reservoir outlet 5122is configured to output the humidified flow of air. The inlet 5118and/or the outlet 5122 are preferably further configured to preventegress of liquid from the reservoir 5110 when the reservoir 5110 isdisplaced and/or rotated from its normal, working orientation. Stillfurther, the inlet 5118 and/or the outlet 5122 are preferably configuredto prevent short-circuiting of the flow of air as described above. Inone form, the inlet 5118 may be configured to prevent ‘spitting’, orsplashing, of liquid which may be caused by a jet of air impinging onthe volume of liquid in the reservoir 5110.

In one arrangement as shown in FIG. 22, the reservoir inlet 5118includes an inlet tube 5124 to provide a flow path for the inlet flow ofair into the reservoir 5110, and the reservoir outlet 5122 includes anoutlet tube 5126 to provide a flow path for the outlet flow ofhumidified air from the reservoir 5110.

In one configuration as shown in FIGS. 26 and 27, it may be advantageousto configure the turning vane 5136 so that the lowest portion of theturning vane 5136 extends below the lowest portion of the outlet tube5126. This may further prevent ingress of water into the inlet tube 5124from any ‘spitting’ of water.

The water reservoir 5110 is preferably configured to provide tiltspillback protection from the water flowing back through the outlet tube5126 or the inlet tube 5124. Water egress through the inlet tube 5124may be particularly undesirable as it may introduce water into the RPTdevice 4000 and damage electronic components (such as an electric motor,a flow sensor or a printed circuit board) from exposure to water.

In one arrangement of the present technology, the reservoir 5110achieves spillback protection by arranging the inlet tube inner end 5125so that when the reservoir 5110 is rotated by 90 degrees in anydirection from its working, horizontal orientation the given maximumvolume of water is able to be stored in the reservoir 5110 withoutreaching the inlet tube inner end 5125.

In another arrangement of the reservoir 5110, the axes of inlet tube5124 and the outlet tube 5126 may intersect when viewed in a plane, suchas from above as shown in FIGS. 28 and 29. The inlet tube 5124 andoutlet tube 5126 may not be connected to each other as one of the tubespasses below the other tube, such as the inlet tube 5124 passes belowthe outlet tube 5126.

This configuration may improve the tilt spillback protection byarranging the inlet tube 5124 and the outlet tube 5126 such that whenthe reservoir 5110 is tilted away from its working orientation, watermust reach the higher end of the inlet tube 5124 or the outlet tube 5126to exit the reservoir 5110. For example, if the reservoir 5110 wastilted such that the water reaches the lower of the inlet tube inner end5125, the water must still rise higher to reach the exterior end of theinlet tube 5124 or the inlet 5118 to exit the reservoir 5110 as shown inFIG. 29.

Simplified representations of the effects created by crossed inlet andoutlet tubing are shown in FIGS. 35 to 38, wherein the internal surfacesare shown by dotted lines. These figures show alternate arrangements ofa water reservoir 5110, with an inlet 5118 and an outlet 5122 thatrespectively include an inlet tube 5124 and an outlet tube 5126. FIGS.35 and 36 show a configuration wherein the axes of the tubing intersectwhen viewed from the side (as shown in FIG. 36), and FIGS. 37 and 38show an alternate configuration wherein the axes of the tubing aresubstantially parallel when viewed from the side (as shown in FIG. 38).In FIGS. 35 to 38, a volume of water 5182 is assumed to fillapproximately half of the volume of the reservoir 5110, and the waterlevel 5184 is indicated by the dotted lines extending horizontally.

When the water reservoir 5110 is oriented as shown in FIGS. 35 and 36,the arrangement of the inlet tube 5124 and the outlet tube 5126 requiresthe water level 5184 to rise above the higher end of the inlet tube 5124or the higher end of the outlet tube 5126 if any water 5182 is to exitthe water reservoir 5110. On the other hand, in the arrangement shown inFIGS. 37 and 38 the water level 5184 only needs to rise as high as alower end of the inlet tube 5124 or the outlet tube 5126 in order toexit the water reservoir 5110.

As the water level 5184 will change as a function of the orientation ofthe water reservoir 5110, this effect of crossing the inlet tube 5124and the outlet tube 5126 may be re-created at any orientation asrequired by re-orienting the inlet tube 5124 and the outlet tube 5126 tosuit the shape of the water reservoir 5110. In some forms, the inlettube 5124 and the outlet tube 5126 may be crossed when viewed frommultiple angles orthogonal to each other.

In the forms shown in FIGS. 28 and 29 and FIGS. 35 to 38, inlet tubeinner end 5125 and the outlet tube inner end 5127 are located within thecavity and the outer end of the inlet tube and the outer end of theoutlet tube 5126 are located in one of the plurality of walls of thecavity at the inlet 5118 and outlet 5122 respectively. A first axis(inlet tube axis) is defined between the inlet tube inner end 5125 andthe inlet 5118 and a second axis (outlet tube axis) is defined by theoutlet tube inner end and the outlet 5122. When the reservoir is tilted(for example by approximately 90° to normal working orientation) thefirst axis is on a first angle such that the inlet tube inner end 5125and the inlet 5118 are positioned at different heights, such that thepredetermined maximum volume of water is below at least one of the inlettube inner end 5125 or the inlet 5118 to prevent spillback of waterthrough the inlet tube 5124. Furthermore, when the reservoir is tilted(for example by approximately 90° to normal working orientation) thesecond axis is on a second angle such that the outlet tube inner end5127 and the outlet 5122 are positioned at different heights, such thatthe predetermined maximum volume of water is below at least one of theoutlet tube inner end 5127 or the outlet 5122 to prevent spillback ofwater through the outlet tube 5126. This effect may be also createdwherein the reservoir is tilted at any other angles, to suit the designand/or tilt conditions of the humidifier 5000 and/or reservoir 5110.

5.5.2.2.9 Reservoir Arrangement with Removable Inlet/Outlet Tubes

In a yet further example of the current technology, the reservoir 5110may be configured as shown in FIGS. 41 a, 41 b, and 42. In this example,the reservoir 5110 comprises a lid portion 5114, an intermediate portion5202 and a base portion 5112 (base portion not shown in FIGS. 41 a and41 b for clarity). The lid portion 5114 and the intermediate portion5202 may be configured to be releasably engaged to each other. They maybe further configured to comprise a number of features when engaged toeach other, such as an inlet 5118, an outlet 5122, an inlet tube 5124and an outlet tube 5126, while being releasably engaged to each other.For example, the lid portion 5114 may comprise an inlet 5118, an outlet5122 and an inlet tube 5124, and the intermediate portion 5202 maycomprise an outlet tube 5126 as shown in FIG. 41 b.

As shown, the intermediate portion 5202 may also comprise a carrier5117, a baffle 5192 and at least one support spoke 5194. The supportspokes 5194 may be provided for structural support and/or to positionthe outlet tube 5126 and/or the baffle 5192 on the intermediate portion.The baffle 5192 is arranged to block a direct air path (orshort-circuiting as described above) between the inlet tube inner end5125 and the outlet tube inner end 5127 to encourage movement of theairflow within the reservoir to improve humidity uptake by the airflowwithin the reservoir 5110. In addition a compliant portion 5116 may beeither integrated with the intermediate portion 5202 as shown or may beformed as separate component to the intermediate portion.

An advantage of this arrangement may be improved cleanability of thereservoir 5110 by separating some of the components from the reservoir,such as the inlet tube 5124 and/or the outlet tube 5126. Thisarrangement may be particularly advantageous in such situations as whenat least one of the inlet tube 5124 or the outlet tube 5126 extends intothe internal volume of the reservoir 5110, as such features may hinderaccess to the interior of the reservoir 5110. It can be seen in FIGS. 41a and 41 b that the intermediate portion 5202 is engaged with the lidportion 5114 in its normal working orientation. However, as theintermediate portion 5202 is separable from the lid portion 5114, theinlet tube 5124 and the outlet tube 5126 may be separated to improveaccess to the interior of the lid portion 5114.

By using two separable portions 5114, 5202 to construct the upperportion of the reservoir and/or configuring the inlet and/or outlettubes 5124, 5126 to be releasably engaged to the reservoir 5110, thenumber of small, difficult-to-access areas may be reduced, which mayimprove cleanability of the reservoir 5110. Furthermore, the removableinlet tube 5124 and/or the removable outlet tube 5126 may be themselvesmore easily accessible for cleaning as well.

In another example of the current technology (not shown), the lidportion 5114 and the intermediate portion 5202 may each comprise partsof a feature, wherein they would combine to form a complete feature. Forinstance, the lid portion 5114 may comprise a part of the inlet tube5124 and a part of the outlet tube 5126, and the intermediate portion5202 may comprise another part of the inlet tube 5124 and another partof the outlet tube 5126. Those skilled in the art will understand thatthe reservoir may be further sub-divided into any number of separableportions, and separable features such as the inlet tube 5124 and/or theoutlet tube 5126 may be located in any number of arrangements inrelation to the separable portions.

Another advantage of the current arrangement may be to improve spillbackperformance (prevention of liquid egress through the inlet tube 5124and/or outlet tube 5126) of the reservoir 5110. Spillback performancemay be improved by increasing the internal volume of the reservoir 5110,which may be achieved by introduction of a void above the inlet tube5124 and/or the outlet tube 5126.

Another method of improving spillback performance is to arrange theinlet tube inner end 5125 and/or the outlet tube inner end 5127 proximalto the center of the reservoir 5110, e.g., proximal to a centroid of thereservoir volume. In this configuration, the maximum water level that isable to be stored in the reservoir 5110 without reaching the inlet tubeinner end 5125 and/or the outlet tube inner end 5127 is the same whenthe reservoir 5110 is rotated by 90 degrees in any direction from itsworking horizontal orientation. In example, such configuration of theinlet tube 5124 and/or outlet tube 5126 may be provided by a singlemolded component, e.g., by combining horizontal and vertical moldingtools to form the inlet tube 5124 and/or outlet tube 5126 in the desiredarrangement. As a reservoir 5110 is typically produced by injectionmolding, forming an inlet tube 5124 and/or an outlet tube 5126 as a partof the lid 5114 prohibits introduction of a void above the inlet tube5124 and/or the outlet tube 5126. In such a configuration, a moldingtool comprising the internal volume of the lid 5114 would be pinned inplace by the inlet tube 5124 and/or the outlet tube 5126 and thusmolding would not be possible, or require a complex and costly toolingarrangement. In such a case, the ability to separate the inlet tube 5124and the outlet tube 5126 may be further advantageous.

It will be understood that the lid portion 5114, the intermediateportion 5202 and the base portion 5112 may be configured in any numberof ways. For instance, the relative sizes of the lid portion 5114 andthe base portion 5112 may vary, and the lid portion 5114 and/or the baseportion 5112 may further comprise multiple materials or components inits construction. One or more of the inlet tube 5124 and the outlet tube5126 may be removably or releasably coupled to the lid portion 5114 orthe base portion 5112, for example as a part of the intermediateportion. The intermediate portion may also be configured to initiallyengage the lid portion 5114 and/or the base portion 5112, for example bybeing configured to be inserted into the lid portion 5114 or the baseportion 5112.

Another feature of this arrangement is the use of support spokes 5194 inorder to provide structural rigidity to the intermediate portion 5202.The spokes 5194, by themselves or in combination with the baffle 5192,may provide a handle for disassembly of the intermediate portion 5202from the lid 5114 or the base portion 5112. This may improve usabilityas the user may grip the baffle 5192 and/or the spokes 5194 to separatethe intermediate portion 5202 from the lid portion 5114 or base portion5112. It should be understood that a number of other configurations maybe possible wherein the support spokes 5194 are arranged alternativelyto the exemplary arrangement as shown in FIGS. 43 and 44.

In an example of the current technology, the baffle 5192 may comprise alocating portion 5196 and a deflector portion 5198 as seen in FIGS. 43a, 43 b, and 44. The locating portion 5196 may be in the form of acylinder to assist in accurately locating the baffle 5192 in relation tothe inlet tube 5124 by fitting around the outside of the verticalportion of the inlet tube 5124, i.e. at the inlet tube inner end 5125.In some forms, the baffle 5192 may further comprise a baffle seal 5197to seal between the baffle 5192 and the inlet tube 5124, for example asshown in FIG. 48 b. The baffle 5192 may also be configured incombination with the spokes 5194 so that at least some portions of thebaffle 5192 may act as a spoke 5194 or vice versa.

An exemplary cross-section of the assembled lid 5114 is shown in FIGS.45 a and 45 b. The diameter of the inlet tube 5124 or the locatingportion 5196 may be varied along its length, for example in afrustro-conical arrangement, so as to progressively engage with eachother. The inlet tube 5124, and the locating portion 5196 may alsoincorporate a complementary retaining mechanism such as aprotrusion/slot combination 5205 as shown in FIGS. 45 a and 45 b.

It is also to be understood that the compliant portion 5116 may belocated at an alternative location to the exemplary arrangements shownin FIGS. 41 a, 41 b, 42, 43 a, 43 b, and 44. For example, the compliantportion 5116 may be formed as a part of the lid portion 5114, as a partof the reservoir base portion 5112, or as a separate component by itselfthat is not integrally formed to any of the lid portion 5114, theintermediate portion 5202 and the base 5112. One exemplary method offorming the compliant portion 5116 with the lid portion 5114 or the base5112 may be by overmoulding or use of a chemical adhesive.

FIG. 46 shows an exploded view of another example of the currenttechnology. In this arrangement, the reservoir 5110 comprises a lidportion 5114, an intermediate portion 5202 and a base portion 5112 (notshown in FIG. 46 for clarity). The intermediate portion 5202 comprisesthe inlet tube 5124 and the outlet tube 5126 as well as a wall portion5206 that is configured to be coupled with the lid portion 5114.Alternatively the intermediate portion 5202 may engage the base portion5112, and may comprise one or both of the inlet tube 5124 and the outlettube 5126. In some cases, the wall portion 5206 that is configured tocouple with the lid portion 5114 may be connected with one or more ofthe inlet tube 5124 and the outlet tube 5126.

This configuration may allow removal of the inlet tube 5124 and/or theoutlet tube 5126 for improved cleanability of the reservoir 5110.Furthermore, this configuration may improve spillback performance of thereservoir 5110 by increasing the internal volume of the reservoir 5110as described above.

In some cases, the inlet tube 5124 and the outlet tube 5126 may bearranged so that removal of either or both of the tubes 5124, 5126 fromthe reservoir 5110 does not affect the predetermined maximum volume ofwater that the reservoir 5110 may retain. Such a configuration may allowcleaning of the tubes 5124, 5126 without removing any water from thereservoir 5110.

5.5.2.2.10 Overfill Prevention

In some prior art humidifier water reservoirs, overfilling of the waterreservoir 5110, for example with a volume of liquid over and above apredetermined, maximum volume of liquid, may reduce effectiveness of aspill prevention feature. For example, if the reservoir 5110 was to berotated away from its intended orientation while overfilled, theoverfilled liquid in the reservoir 5110 may reach the inlet 5118 at alower angle of tilt than if the reservoir 5110 had been only filled withthe predetermined, maximum volume of liquid. As a result, some prior arthumidifier water reservoirs have included a water filling indicationmark to reduce occurrence of such overfilling, however this may only gosome way towards ameliorating this risk as the user (e.g. patient 1000may not be able to see, or be aware of the meaning of, the indicationmark for example.

Some prior art humidifier water reservoirs comprise one or more tubes,which can act as egress paths for liquid (typically water) when thereservoir is filled with a volume of liquid which exceeds a thresholdvolume. One example of such prior art humidifier is described in PCTpublication WO 2009/156921. However, one disadvantage of such anarrangement may be that if the reservoir is filled to this thresholdvolume, any movement of the reservoir may lead to egress of liquid fromthe reservoir (e.g. from movement of the volume of liquid).Consequently, transport of such a reservoir (e.g. from the patient'skitchen or bathroom) without spillage may be difficult, and the risk ofspillage during usage (i.e. through the one or more tubes of thereservoir) may be high. Consequently, such prior art humidifier waterreservoirs often comprise a water filling indication mark indicating therecommended predetermined maximum volume of water that the reservoir isto be filled with, where the recommended predetermined maximum volume ofwater is below (sometimes significantly below) the threshold volume atwhich water may begin to spill out of the one or more tubes in thereservoir. In some cases, such prior art humidifier water reservoirs mayfurther comprise a secondary chamber configured to contain the waterwhich has escaped the reservoir, for example before the water may enterthe RPT device located upstream.

Another aspect of this technology is the inclusion of one or moreoverfill protection features configured to prevent filling the reservoirabove the maximum volume of water when filling the humidifier reservoir,such as in its open configuration and/or the closed configuration.

In one arrangement as seen in FIGS. 30 a and 30 b, an overfillprotection feature may include at least one orifice 5138 in the waterreservoir 5110 to indicate over-filling. According to this aspect of thetechnology, when the water reservoir 5110 is being filled with thereservoir lid 5114 open, any water that is introduced into the reservoir5110 beyond a predetermined maximum volume of the reservoir 5110 wouldspill out from the orifice 5138. This would indicate to the user thatthe reservoir 5110 is full, as well as preventing such overfilling.Advantageously water would spill out only through the at least oneorifice 5138 rather than from all areas of the water reservoir resultingin less overflow spillage for the user to clean up. Thus, the at leastone orifice defines egress path(s) of water when the predeterminedmaximum volume of water is exceeded. FIG. 30 a shows the water reservoir5110 in its open configuration, wherein an upper flange or lip 5224 ofthe base 5112 does not span the perimeter of the entire opening,creating an orifice 5138. FIG. 30 b shows a portion of the base 5112indicating the at least one orifice 5138. The at least one orifice 5138may be in the form of one or more apertures, holes, slits or slots, orany other form that allows communication of fluid into and out of thewater reservoir 5110. The at least one orifice 5138 may be formed in oneor more positions around the upper flange or lip 5224 of the base 5112.

In an alternate arrangement, the overfill protection feature may includea sloped profile 5139. As shown in FIGS. 30 c and 30 d, the reservoirbase 5112 may be arranged so that its side profile has a sloped profile5139 in one or more directions. This arrangement may also indicateover-filling when the reservoir base 5112 is filled with water. In thisarrangement, when the reservoir lid 5114 is in its open configuration,water may spill out at the base of the sloped profile 5139 rather thanfrom all areas of the reservoir. Thus, the sloped profile defines anegress path of water when the predetermined maximum volume of water isexceeded. Advantages of the above methods may be that over-filling maybecome more difficult than has been in the prior art, and presentsanother advantage that in response to attempted over-filling, spillagemay occur at more predictable locations.

In the examples of the at least one orifice 5138 and the sloped profile5139 described above, the overfill protection feature is independent ofthe inlet tube 5124 and the outlet tube 5126. That is, the egress pathof water is provided by the at least one orifice 5138 or the slopedprofile 5139 rather than spilling out via the inlet tube 5124 and/or theoutlet tube 5126.

In one form, when the water reservoir 5110 is in its closedconfiguration, a threshold volume of water which is required for thewater to reach the inlet tube 5124 and/or the outlet tube 5126, and thusfor the tubes 5124, 5126 to define an egress path of water, may belarger than the predetermined maximum volume of water. Such anarrangement may allow for a reduced risk of water egress from thereservoir 5110 during its transport or in use.

In some cases, the reservoir 5110 may comprise at least one waterfilling indication mark 5140 (e.g. on the base 5112 as shown in FIGS. 57a and 57 b). The water filling indication mark 5140 may indicate to theuser the predetermined maximum volume of water for the reservoir 5110 tocontain, such as by indicating a water level which the reservoir 5110 isto be filled to. Further water filling indication marks 5140 _(—) a,5140 _(—) b (e.g., as shown in FIG. 57 a and 57 b) may indicate thelevel of fill of the reservoir 5110. In one arrangement (as shown inFIGS. 57 a and 57 b), the reservoir 5110 may be further configured sothat the predetermined maximum volume of water is substantiallyidentical to a maximum volume of water which will remain in thereservoir without causing egress via the at least one orifice 5138 asshown (or the sloped profile 5139—not shown). Thus, when the user (e.g.patient 1000 attempts to fill the reservoir 5110 beyond the waterfilling indication mark 5140, the user would cause water egress via theat least one orifice 5138 or the sloped profile 5139.

The reservoir 5110 may be further configured, for example as shown inFIGS. 58 a and 58 b, so that when the reservoir 5110 is in its closedconfiguration, a threshold volume of water required for the water(indicated by water line 5141_2) to reach the inlet tube 5124 and/or theoutlet tube 5126 may be a greater volume than the predetermined maximumvolume of water (indicated by water line 5141_1). As shown in FIG. 58 b,the water line at the predetermined maximum volume of water 5141_1 maybe substantially in line with a base or lower edge of the at least oneorifice 5138 to allow egress of any excess water that is added above thewater filling indication mark 5140. Such an arrangement may allow thepatient 1000 to more easily transport the reservoir 5110 while itcontains the predetermined maximum volume of water, as well as reduce arisk of water spillage/egress while the humidifier 5000 is in use.

In an alternative example, the base or lower edge of the at least oneorifice 5138 or sloped profile 5139 may be above the predeterminedmaximum volume of water (indicated by water line 5141_1) but below thethreshold volume of water (indicated by water line 5141_2). Preferably,the base or lower edge of the at least one orifice 5138 or slopedprofile 5139 may be closer to the predetermined maximum volume of water(indicated by water line 5141_1) than the threshold volume of water(indicated by water line 5141_2).

Another aspect of this technology is that when the water reservoir 5110is in its closed configuration, a compliant portion 5116 sealinglyengages the base 5112 and the reservoir lid 5114 and blocks or seals theorifice 5138 or sloped profile 5139 preventing fluid communication intoand out of the water reservoir 5110. One arrangement of this feature isshown in FIG. 31 a, which shows that when the reservoir lid 5114 isclosed (lid not shown in this image), the compliant portion 5116sealingly engages with the base 5112 on the outside of the orifice 5138and no longer allows communication of liquid or air into and out of thewater reservoir 5110 through the orifice 5138. Similarly the compliantportion 5116 would engage with the base 5112 to surround the edges ofthe sloped profile preventing communication of liquid or air into andout of the water reservoir 5110 through the sloped profile 5139 as shownin FIG. 31 b.

According to another aspect of the present technology, an overfillprevention feature may be configured to prevent overfilling when a useris attempting to fill the reservoir 5110 while in its closedconfiguration, for example via the inlet 5118 or outlet 5122.

In one form (shown in FIG. 49 without the reservoir base 5112), theoverfill prevention feature may form one or more air locks to preventfurther ingress of liquid into the reservoir 5110 when the predeterminedmaximum volume of liquid is in the reservoir 5110. In this form, whenfilling the reservoir 5110 in its closed configuration via the inlet5118 or outlet 5122, one or more air locks would form an enclosure ofair in the reservoir 5110 that is not displaced by the volume of liquidin the reservoir 5110. In an example shown in FIG. 49, the reservoir5110 is in an orientation such that the normal to the inlet 5118 and theoutlet 5122 are oriented vertically, as a user would orient thereservoir 5110 while filling it with water. The water level 5184 wouldrise, and reach the level shown on FIG. 49, whereupon the remainingvolume of air in the reservoir 5110 is no longer able to access theinlet tube 5124 or the outlet tube 5126, therefore would no longer beable to escape from the reservoir 5110. The reservoir 5110 would thusnot be able to receive any further volume of water into its interiorvolume. Adding further water would fill the inlet tube 5124 or theoutlet tube 5126 depending upon whether the reservoir was being refilledthrough the inlet 5118 or the outlet 5122 respectively and then overflowout of the inlet 5118 or outlet 5122 respectively. This would indicateto the user that the reservoir 5110 was being overfilled.

Preferably, the volume of water in the reservoir 5110 when any furtheringress of water into the reservoir 5110 is prevented by formation ofthe one or more air locks is substantially equal to the predeterminedmaximum volume of liquid to be retained in the reservoir 5110. In somecases, the reservoir 5110 may allow further filling of the inlet tube5124 and/or the outlet tube 5126 although further ingress of water intothe interior volume is prevented by the air locks. In such cases, thevolume of liquid in the reservoir 5110 when the air locks are formed, aswell as the volume of the inlet tube 5124 and/or the outlet tube 5126may be configured so that when added together, they are substantiallyequal to the predetermined maximum volume of liquid to be retained inthe reservoir 5110.

In some cases, for example where the normal to the inlet 5118 and theoutlet 5122 may not be parallel, a user may fill the reservoir 5110 inone of a multiple orientations while closed. In such cases, thereservoir 5110 may be configured such that the appropriate air locks areformable at one of, or a plurality of the multiple orientations. The airlocks need not be formed solely by occlusion of the inlet tube 5124and/or the outlet tube 5126. In some forms (not shown), one or more airlocks may be formed by occlusion of any cavities or ports which mayallow fluid communication between the interior and the exterior of thereservoir 5110. Furthermore, the occlusion need not be performed by thevolume of liquid in the reservoir 5110. In some forms, the volume ofliquid, as it is increased, may deform or move another component to forma seal (and thus an air lock) in the reservoir.

5.52.2.11 Collapsible Inlet/Outlet Tube

As described above, any spillage of water from the reservoir 5110,especially through the inlet tube may be undesirable. One scenario wherespillage of water may occur is when the reservoir 5110 and/or thehumidifier 5000 is tilted away from its normal, working orientation, forexample by its user (e.g., patient 1000. Tilting of the reservoir 5110and/or the humidifier 5000 may occur while the patient 1000 is notreceiving therapy, for example as the humidifier 5000 is picked up to bemoved and/or packed away.

The humidifier 5000 may comprise one or more collapsible tubes, such acollapsible inlet tube and/or a collapsible outlet tube. A collapsibletube 5208 may be able to assume one of a plurality of configurationssuch as an open state (shown in FIG. 55 a), and a closed state (shown inFIG. 55 b). In some cases, the collapsible tube may be able to assumevarious degrees of ‘openness’ therebetween, such as 20%, 40%, 60% or 80%(e.g. as measured by a percentage of a ‘fully open’ cross section area).

The collapsible tube may comprise a flexible portion 5210, which may beconfigurable between a plurality of states to close or open thecollapsible tube 5208 as shown in FIG. 55 a and FIG. 55 b (flexibleportion 5210 marked by dotted boundaries). Alternatively, oradditionally, the collapsible tube 5208 may comprise a rigid portion5212 to locate and/or support the flexible portion 5210. In some forms,the rigid portion 5212 may comprise approximately half (50%) of thecollapsible tube 5208 (e.g., in cross section), however other portionssuch as 30%, 40%, 60%, 70% may be also suitable according to thespecific configuration of the collapsible tube 5208.

In one form, the collapsible tube may be biased towards one state, suchas an open state, and may assume another state, such as a closed state,upon occurrence of an event, such as impingement of water onto thecollapsible tube, orientation of the reservoir 5110 (and thusorientation of the collapsible tube). In another form, the collapsibletube may be biased towards a closed state, and further configured toassume an open state when acted upon by a flow of pressurised air, forexample when the RPT device 4000 is switched on. In some forms, thecollapsible tube may be biased towards that latest state that thecollapsible tube had assumed. That is, if a flow of pressurised gasforced the collapsible tube into the open state, it may remain that wayuntil it is forced into the closed state.

The collapsible tube 5208 may be constructed in any one of a number ofsuitable arrangements, one of which may be by overmoulding the flexibleportion 5210 onto the rigid portion 5212. In other arrangements, theflexible portion 5210 and the right portion 5212 may be constructedseparately and fastened together such as by a snap fit, or a one-waypermanent latch, or by use of adhesives. In one form, the flexibleportion 5210 of the collapsible tube 5208 may extend over an entirelength of the collapsible tube 5208, in which case the flexible portion5210 and the rigid portion 5212 may be joined at or around thecircumference of the collapsible tube 5208. In another form, theflexible portion 5210 may only extend over a part of the entire lengthof the collapsible tube 5208, so that the flexible portion 5210 and therigid portion 5212 may be joined at or around the circumference of thecollapsible tube 5208, as well as to abut each other. Any number ofother arrangements of a collapsible tube (e.g., in geometry,construction, composition) may be suitable to achieve the same effectsas those described in the present disclosure.

In an example of the present technology which is shown in FIG. 56, ahumidifier lid 5114 is shown comprising an inlet tube 5124 and an outlettube 5126. In this example, the inlet tube 5124 comprises a rigidportion 5212 towards a top of the inlet tube 5124, and a flexibleportion 5210 (shaded portion in FIG. 56) towards the bottom of the inlettube 5124. Thus, in one arrangement, the flexible portion 5210 may bebiased towards an open configuration and collapse only as a pressurefrom the volume of water acts upon an exterior of the flexible portion5210 (e.g., from within the reservoir 5110. In another arrangement, theflexible portion 5210 may be biased towards a closed configuration andopen only when a flow of pressurised air is delivered into the reservoir5110 from the reservoir inlet 5118.

Use of a collapsible tube may be advantageous in that the volume of thecollapsed tube may be effectively added to the interior of thereservoir, thereby lowering a depth of the volume of water in thereservoir. This may have two outcomes, one of reducing a likelihood ofthe volume of water in the reservoir reaching an opening of the inlettube and/or an outlet tube, and another of allowing a size of thereservoir to be smaller than would be otherwise possible. Anotheradvantage of a collapsible tube may be that it may be able to act as aone-way valve, by either closing when reached by water and/or openingwhen a flow of pressurised air reaches it.

5.5.2.2.12 Retaining Clip

The reservoir lid 5114 may include a feature by which the waterreservoir 5110 is to be retained in the water reservoir dock 5130 oncethe two members are engaged with each other. In one arrangement aretaining feature may be a protrusion, or a clip, 5142 on the reservoirlid 5114 as shown in FIGS. 32 to 33. FIGS. 32 to 33 show a waterreservoir 5110 and the reservoir dock 5130. Here, a protrusion, or aclip, 5142 on the reservoir lid 5114 removably engages with acorresponding dock locking recess 5144 in the water reservoir dock 5130when the water reservoir 5110 is inserted into the water reservoir dock5130. This connection secures the water reservoir 5110 relative to thewater reservoir dock 5130.

As described above the compliant portion 5116 of the reservoir iscompressed to enable insertion of the reservoir into the dock 5130. Thecompression of the compliant portion 5116 allows a portion of thereservoir 5110 to slide into the dock 5130 and allows the protrusion (orclip) 5142 to slide initially under the outer edge surface of the dock5130 to reach the dock locking recess 5144. The compression forceapplied to the reservoir for insertion may then be released to allow theprotrusion (or clip) 5142 to engage with the dock locking recess 5144and securing of the reservoir 5110 within the dock 5130. When thereservoir 5110 is secured within the dock 5130 the compliant portion5116 is no longer in or in a reduced compressed state. Similarly, inorder to be able to remove the water reservoir 5110 from the waterreservoir dock 5130, the compliant portion 5116 must be compressed as todisengage the lid protrusion 5142 from the dock locking recess 5144.

The lid protrusion 5142 may be further configured with a taper as shownin FIG. 33. The taper may be directed to increase in height away fromthe direction of insertion, to increase the amount of interferencebetween the protrusion 5142 and the dock 5130 progressively duringinsertion. It would be clear to those skilled in the art that in analternative arrangement the lid protrusion 5142 may be a recess, and thedock locking recess 5144 may be a corresponding protrusion.Alternatively one of any number of retaining features that are known inthe art may be used to achieve the same outcomes as described above.

5.5.2.3 Heater Plate 5120

A heater plate 5120 is used to transfer heat to the water reservoir5110.

The heater plate 5120 may form a part of the reservoir dock 5130, andmay be located on or near the base of the humidifier 5000 as shown inFIG. 14. The heater plate 5120 may be formed, for example, of a nickelchrome alloy, stainless steel or anodised aluminium. The heater plate5120 may comprise a heating element 5240, for example a layered heatingelement such as one described in the PCT Patent Application PublicationNumber WO 2012/171072, the entire document of which is incorporatedherewithin by reference.

5.5.2.4 Humidifier End Cap 5300

In one example of the present technology as shown in FIG. 59, thehumidifier 5000 may comprise a humidifier end cap 5300 configured todirect the flow of air from the RPT device 4000 to the humidifier outlet5172. In some arrangements when humidification is not required and thehumidifier 5000 is integrated with the RPT device 4000, the humidifier5000 may comprise an end cap in lieu of a humidifier reservoir 5000. Asshown in FIG. 59, the humidifier end cap 5300 may be configured to bereceived in the water reservoir dock 5130 interchangeably with thereservoir 5110.

In one form, as shown in FIGS. 59 and 60, the humidifier end cap 5300may comprise an end cap inlet 5310 for receiving the flow of air (e.g.from the dock outlet 5168), an end cap outlet 5320 for delivering theflow of air (e.g. to the dock air inlet 5170 and an end cap latch 5330for locking and/or releasing the end cap 5300 to/from the waterreservoir dock 5130.

The end cap 5300 may comprise an identification element, to allow acontroller, such as the central controller 4230 or the humidifiercontroller 5250, to detect its presence (or absence), for example in thereservoir dock 5130. The reservoir dock 5130 may comprise acomplementary detection element, to detect the presence (or absence) ofthe end cap 5300. In one form, detection of the presence or absence ofthe humidifier controller 5250 may cause the controller to perform onemore of: switch off/on the heater plate 5120, adjust the power output ofthe heater plate 5120, switch off/on the heated air circuit 4171, adjustthe power output of the heated air circuit 4171, adjust the pressuredrop estimation between the pressure generator 4140 and the patientinterface 3000, disable/enable user interface elements relating tooperation of the humidifier 5000, or disable/enable data logging/datareporting relating to operation of the humidifier 5000. In one form, asshown in FIG. 59 and FIG. 60, the humidifier end cap 5300 may comprisean identification element (shown in the form of a magnet 5340 disposedon the end cap 5300, such as in an end cap magnet holder 5345. Theidentification element may be used for detection of the humidifier endcap 5300 by the controller via the detection element, for example thedetection element may include a Hall Effect sensor located in or nearthe reservoir dock 5130 (not shown) such as on a printed circuit board(PCB) in the RPT device 4000.

One advantage of an end cap 5300 comprising an identification element,may be to allow reduced power consumption or customised operation of thehumidifier 5000 where an end cap 5300 is used. A further advantage ofhaving the heater plate on by default and turned off by engagement ofthe end cap 5300 is in a single step of installing the end cap both theheater plate 5120 is deactivated and access to the heater plate isprevented.

Yet further, where a manufacturer may produce more systems that includehumidifiers 5000 with a reservoir 5110 than systems that include an endcap 5300, it may be advantageous for the manufacturer (e.g., costs) toplace the identification element on the end cap 5300, as theidentification element, may incur additional cost (or time) to whichevercomponent (i.e., reservoir 5110 or the end cap 5300 that it may becoupled to.

5.5.3 Humidifier Electrical & Thermal Components 5200

A humidifier 5000 may comprise a number of electrical and/or thermalcomponents such as those listed below.

5.5.3.1 Sensor 5270

A humidifier 5000 may comprise one or more sensors 5270, such as an airpressure sensor(s), an air flow sensor(s), a temperature sensor(s)and/or a relative humidity sensor(s). A sensor may produce an outputsignal indicating the property that it measures, and the output signalmay be communicated to a controller such as the central controller 4230and/or the humidifier controller 5250. In some forms, a sensor may belocated externally to the humidifier 5000 (such as in the air circuit4170 or in an external module) while communicating the output signal tothe controller.

5.5.3.1.1 Flow Sensor

A flow sensor may be provided to a humidifier 5000 in addition to, orinstead of, a flow sensor 4274 provided in the RPT device 4000.

5.5.3.1.2 Temperature Sensor(s)

A humidifier 5000 may comprise a temperature sensor which may beconfigured to measure a temperature of the heating element 5240 and/or atemperature of the flow of air in the reservoir 5110. In some forms, thehumidifier 5000 may further comprise a temperature sensor to detect thetemperature of the ambient air.

5.5.3.1.3 Humidity Sensor(s)

In one form, the humidifier 5000 may comprise a humidity sensor todetect a relative humidity of the ambient air. The humidity sensor maybe an absolute humidity sensor or a relative humidity sensor. When arelative humidity sensor is used, a value of absolute humidity may bedetermined based on measured values of relative humidity and temperatureof the flow of the air.

5.5.3.2 Heating Element(s) 5240

The heating element 5240 may be a heat generating component such as anelectrically resistive heating track. One suitable example of a heatingelement 5240 is a layered heating element such as one described in thePCT Patent Application Publication Number WO 2012/171072, the entiredocument of which is incorporated herewithin by reference.

5.5.3.3 Heated Air Circuit 4171

A heated air circuit 4171 may be used in addition to, or instead of, theair circuit 4170. Temperature of the flow of air that is output from thehumidifier 5000 may be higher than ambient temperature. As a result,heat loss may occur from the flow of air to the ambient air, therebyincreasing the relative humidity of the humidified flow of air. In somecases, condensation may occur where the relative humidity increases toat or near 100% RH.

In one form, the humidifier 5000 may comprise, or be connected to, aheated air circuit 4171. Use of a heated air circuit 4171 may prevent orreduce condensation of water from the flow of air as it travels from thehumidifier 5000 to the patient interface 3000. For instance the heatedair circuit 4171 may provide heat to the flow of air to compensate forheat loss to the ambient air.

The heated air circuit 4171 may comprise one or more sensors, such as atemperature sensor and/or a humidity sensor. Use of a temperature sensorand/or a humidity sensor may help determine the temperature and/orhumidity (absolute and/or relative) in the heated air circuit 4171, forexample at its outlet. In some cases, the heated air circuit 4171 maycomprise a heating element 5240, such as a heated coil, configured toprovide a heat input to the heated air circuit 4171.

5.5.3.4 Humidifier Controller 5250

According to one arrangement of the present technology, a humidifier5000 may comprise a humidifier controller 5250 as shown in FIG. 5 b. Inone form, the humidifier controller 5250 may be a part of the centralcontroller 4230. In another form, the humidifier controller 5250 may bea separate controller, which may be in communication with the centralcontroller 4230.

In one form, the humidifier controller 5250 may receive as inputs (e.g.from sensors 5270 measures of characteristics (such as temperature,humidity, pressure and/or flow rate), for example of the flow of air,the water in the reservoir 5110 and/or the humidifier 5000. Thehumidifier controller 5250 may also be configured to execute orimplement humidifier algorithms and/or deliver one or more outputsignals.

As shown in FIG. 5 b, the humidifier controller may comprise a pluralityof controllers, such as a central humidifier controller 5251, a heatedair circuit controller 5254 configured to control the temperature of aheated air circuit 4171 and/or a heating element controller 5252configured to control the temperature of a hot plate. The heated aircircuit controller 5254 may receive an input from one or more sensors tocontrol operation of the heated air circuit 4171. As an example, theheated air circuit controller 5254 may receive from sensors 5270 thetemperature and the relative humidity of the humidified flow of air toadjust the heat output by the heated air circuit 4171.

5.6 GLOSSARY

For the purposes of the present technology disclosure, in certain formsof the present technology, one or more of the following definitions mayapply. In other forms of the present technology, alternative definitionsmay apply.

5.6.1 General

Air: Air will be taken to include breathable gases, for exampleatmospheric air with supplemental oxygen.

Continuous Positive Airway Pressure (CPAP): CPAP treatment will be takento mean the application of a supply of air to the entrance to theairways at a pressure that is continuously positive with respect toatmosphere.

5.6.2 Aspects of RPT Devices

Air circuit: A conduit or tube constructed and arranged in use todeliver a supply of air between an upstream component (such as a RPTdevice) and a downstream component (such as a patient interface). Inparticular, the air circuit may be in fluid connection with the outletof the pneumatic block and the patient interface.

The air circuit may be referred to as air delivery tube. In some casesthere may be separate limbs of the circuit for inhalation andexhalation. In other cases a single limb is used.

5.6.3 Humidifiers

Water reservoir: A water reservoir (also commonly referred to as a watertub, humidifier tub or a humidifier reservoir) is a chamber configuredto contain a body/volume of liquid (e.g., water) used to add humidity tothe flow of air.

5.6.4 Materials

Silicone or Silicone Elastomer: A synthetic rubber. In thisspecification, a reference to silicone is a reference to liquid siliconerubber (LSR) or a compression moulded silicone rubber (CMSR). One formof commercially available LSR is SILASTIC (included in the range ofproducts sold under this trademark), manufactured by Dow Corning.Another manufacturer of LSR is Wacker. Unless otherwise specified to thecontrary, a preferred form of LSR has a Shore A (or Type A) indentationhardness in the range of about 35 to about 45 as measured using ASTMD2240

Polycarbonate: a typically transparent thermoplastic polymer ofBisphenol-A Carbonate.

5.7 Other Remarks

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent file or records, but otherwise reserves all copyrightrights whatsoever.

Unless the context clearly dictates otherwise and where a range ofvalues is provided, it is understood that each intervening value, to thetenth of the unit of the lower limit, between the upper and lower limitof that range, and any other stated or intervening value in that statedrange is encompassed within the technology. The upper and lower limitsof these intervening ranges, which may be independently included in theintervening ranges, are also encompassed within the technology, subjectto any specifically excluded limit in the stated range. Where the statedrange includes one or both of the limits, ranges excluding either orboth of those included limits are also included in the technology.

Furthermore, where a value or values are stated herein as beingimplemented as part of the technology, it is understood that such valuesmay be approximated, unless otherwise stated, and such values may beutilized to any suitable significant digit to the extent that apractical technical implementation may permit or require it.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this technology belongs. Although any methods andmaterials similar or equivalent to those described herein can also beused in the practice or testing of the present technology, a limitednumber of the exemplary methods and materials are described herein.

When a particular material is identified as being preferably used toconstruct a component, obvious alternative materials with similarproperties may be used as a substitute. Furthermore, unless specified tothe contrary, any and all components herein described are understood tobe capable of being manufactured and, as such, may be manufacturedtogether or separately.

It must be noted that as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include their plural equivalents,unless the context clearly dictates otherwise.

All publications mentioned herein are incorporated by reference todisclose and describe the methods and/or materials which are the subjectof those publications. The publications discussed herein are providedsolely for their disclosure prior to the filing date of the presentapplication. Nothing herein is to be construed as an admission that thepresent technology is not entitled to antedate such publication byvirtue of prior invention. Further, the dates of publication providedmay be different from the actual publication dates, which may need to beindependently confirmed.

Moreover, in interpreting the disclosure, all terms should beinterpreted in the broadest reasonable manner consistent with thecontext. In particular, the terms “comprises” and “comprising” should beinterpreted as referring to elements, components, or steps in anon-exclusive manner, indicating that the referenced elements,components, or steps may be present, or utilized, or combined with otherelements, components, or steps that are not expressly referenced.

The subject headings used in the detailed description are included onlyfor the ease of reference of the reader and should not be used to limitthe subject matter found throughout the disclosure or the claims. Thesubject headings should not be used in construing the scope of theclaims or the claim limitations.

Although the technology herein has been described with reference toparticular examples, it is to be understood that these examples aremerely illustrative of the principles and applications of thetechnology. In some instances, the terminology and symbols may implyspecific details that are not required to practice the technology. Forexample, although the terms “first” and “second” may be used, unlessotherwise specified, they are not intended to indicate any order but maybe utilised to distinguish between distinct elements. Furthermore,although process steps in the methodologies may be described orillustrated in an order, such an ordering is not required. Those skilledin the art will recognize that such ordering may be modified and/oraspects thereof may be conducted concurrently or even synchronously.

It is therefore to be understood that numerous modifications may be madeto the illustrative examples and that other arrangements may be devisedwithout departing from the spirit and scope of the technology.

While the present technology has been described in connection with whatare presently considered to be the most practical and preferredexamples, it is to be understood that the technology is not to belimited to the disclosed examples, but on the contrary, is intended tocover various modifications and equivalent arrangements included withinthe spirit and scope of the technology. Also, the various examplesdescribed above may be implemented in conjunction with other examples,e.g., aspects of one example may be combined with aspects of anotherexample to realize yet other examples. Further, each independent featureor component of any given assembly may constitute an additional example.

5.8 ADDITIONAL TECHNOLOGY EXAMPLES Example 1

The apparatus for humidifying a flow of air, comprising:

-   -   a heater plate;    -   a chamber in fluid communication with the flow of air, and    -   a reservoir comprising a conductive portion in thermal        engagement with the heater plate,    -   the apparatus configured so that varying a first pressure of the        flow of air in the chamber varies a level of thermal engagement        between the conductive portion and the heater plate.

Example 2

The apparatus as described in example 1, wherein the reservoir furthercomprises an inlet and an outlet.

Example 3

The apparatus as described in example 2, wherein the thermal engagementis in a first direction that is substantially normal to a surface of theconductive portion.

Example 4

The apparatus as described in any one of examples 1-3, furtherconfigured to vary a magnitude of a force between the conductive portionand the heater plate in the first direction as the first pressure isvaried.

Example 5

The apparatus as described in any one of examples 1-4, wherein thechamber is part of the reservoir.

Example 6

The apparatus as described in any one of examples 1-5, wherein thechamber further comprises a compliant portion.

Example 7

The apparatus as described in any one of examples 1-6, wherein theapparatus further comprises a dock configured to receive the reservoir,and the dock comprises the heater plate.

Example 8

The apparatus as described in example 7, wherein the dock furthercomprises a cavity having a top portion and a bottom portion, the bottomportion having the heater plate located thereon, the cavity configuredto retain at least a portion of the reservoir therein.

Example 9

The apparatus as described in example 8, wherein the compliant portionis compressed to enable insertion of the reservoir into the cavity ofthe dock.

Example 10

The apparatus as described in any one of examples 8 or 9, wherein thetop portion of the cavity is moveable between an open and closedconfiguration to facilitate insertion of the reservoir into the cavity.

Example 11

The apparatus as described in any one of examples 6-10, wherein thecompliant portion is configured to adjust in size as the first pressureis varied to vary the level of thermal engagement between the heaterplate and the conductive portion.

Example 12

The apparatus according to any one of examples 1-11, wherein thereservoir further includes a base and a lid, the base structured to holda volume of liquid and including the conductive portion.

Example 13

The apparatus according to example 12, wherein the base and lid arepivotably coupled together.

Example 14

The apparatus according to any one of examples 12-13, wherein thecompliant portion forms a seal between the base and lid.

Example 15

The apparatus according to any one of examples 12-14, wherein thereservoir further includes a latch to secure the base and lid together.

Example 16

The apparatus according to any one of examples 7-15, wherein thereservoir further comprises at least one handle to facilitate couplingof the reservoir to the dock.

Example 17

The apparatus according to any one of examples 8-16 wherein thereservoir further includes a retaining clip adapted to engage with arecess on the dock to retain the reservoir in the cavity of the dock.

Example 18

The apparatus according to any one of examples 7 to 17, wherein thereservoir is structured to prevent refilling of the reservoir when thereservoir is coupled to the dock.

Example 19

The apparatus according to example 18, wherein at least a portion of thereservoir is prevented from being opened when the reservoir is coupledto the dock.

Example 20

The apparatus according to any one of examples 18 or 19, wherein thereservoir includes a re-filling cap.

Example 21

The apparatus according to any one of examples 1-20, further comprisingan overfill protection element configured to prevent filling thereservoir above a predetermined maximum volume of water.

Example 22

The apparatus according to example 21, wherein the overfill protectionelement comprises at least one orifice formed in a wall of thereservoir, the at least one orifice defines an egress path of water whenthe predetermined maximum volume of water is exceeded.

Example 23

The apparatus according to example 21, wherein the overfill protectionelement comprises a sloped profile in the side profile of a wall of thereservoir, the sloped profile defines an egress path of water when thepredetermined maximum volume of water is exceeded.

Example 24

A method for varying thermal contact between a heater plate and areservoir in a humidification system for humidifying a flow of air, themethod comprising:

-   -   varying a pressure of the flow of air in the reservoir that is        in fluid communication with the flow of air to vary a force        between the heater plate and the reservoir.

Example 25

An apparatus for humidifying a flow of air, comprising:

-   -   a heater plate; and    -   a reservoir comprising:    -   an inlet to receive the flow of air;    -   an outlet; and    -   a conductive portion in thermal contact with the heater plate,    -   and wherein the apparatus is configured so that varying a        pressure of the flow of air in the reservoir varies a force        between the heater plate and the conductive portion in a        direction of thermal contact.

Example 26

The apparatus as described in example 25, further comprising a dockconnectable with the reservoir.

Example 27

The apparatus as described in example 26, wherein the dock is configuredto constrain the reservoir from opening in the direction of thermalcontact.

Example 28

A reservoir configured to contain a volume of liquid for humidifying apressurised flow of air, comprising:

-   -   a base portion comprising a conductive portion;    -   a lid portion comprising an inlet and an outlet; and    -   a compliant portion    -   wherein the base portion and the lid portion are pivotably        engaged and configurable in an open configuration and a closed        configuration while pivotably engaged, and the seal sealingly        engages the base portion and the lid portion when the reservoir        is in the closed configuration.

Example 29

The reservoir as described in example 28, wherein the compliant portioncomprises an outlet tube, and a baffle, the baffle being configured toconnect to the inlet tube.

Example 30

An apparatus for humidifying a flow of air, comprising:

-   -   a heater plate; and    -   a reservoir comprising:    -   an inlet;    -   an outlet;    -   a compliant portion; and    -   a conductive portion in thermal contact with the heater plate,    -   wherein the apparatus is configured so that varying a height of        the compliant portion varies a level of thermal engagement        between the conductive portion and the heater plate.

Example 31

The apparatus as described in example 30, wherein the apparatus isconfigured so that the thermal engagement is in a first direction thatis substantially normal to a surface of the conductive portion.

Example 32

A method of varying a level of thermal engagement in a humidifierapparatus, the method comprising:

-   -   (i) thermally engaging a heater plate with a conductive portion        of a reservoir, and    -   (ii) varying a height of a compliant portion of the reservoir to        vary a level of thermal engagement between the conductive        portion and the heater plate.

Example 33

A water reservoir for a humidifier apparatus, the reservoir comprising:

-   -   a plurality of walls forming a cavity to hold the a        predetermined maximum volume of water;    -   an inlet tube for receiving a supply of air into the reservoir,        the inlet tube comprising an inner end and an outer end; and    -   an outlet tube for delivering a supply of air from the        reservoir, the outlet tube comprising an inner end and an outer        end;    -   wherein the inlet tube and the outlet tube are configured that        when the reservoir contains the predetermined maximum volume of        water, at least one of the inner end or the outer end of the        inlet tube, and at least one of the inner end or the outer end        of the outlet tube are above the predetermined maximum volume of        water regardless of an orientation of the reservoir.

Example 34

A water reservoir for a humidifier apparatus, the reservoir comprising:

-   -   an inlet tube for receiving a supply of air into the reservoir;    -   an outlet tube for delivering a supply of air from the        reservoir;    -   wherein at least one of the inlet tube or the outlet tube is        able to assume at least two configurations.

Example 35

The water reservoir as described in example 34, wherein the at least twoconfigurations comprises an open configuration and a closedconfiguration.

Example 36

The water reservoir as described in example 35, wherein the at least oneor the inlet tube or the outlet tube is collapsible to form the closedconfiguration.

5.9 REFERENCE SIGNS LIST

Number Feature Item 1000 patient 3000 patient interface 3100seal-forming structure 3200 plenum chamber 3300 stabilising structure3600 connection port 4000 RPT device 4010 external housing 4020pneumatic block 4100 pneumatic components 4110 air filter 4112 inlet airfilter 4114 outlet air filter 4120 muffler 4122 inlet muffler 4124outlet muffler 4140 pressure generator 4142 blower 4144 motor 4160anti-spillback valve 4170 air circuit 4171 heated air circuit 4180supplemental oxygen 4200 electrical components 4230 central controller4240 therapy device controller 4270 transducer 4274 flow sensor 4300algorithms 5000 humidifier 5100 humidifier mechanical components 5110water reservoir 5112 reservoir base 5114 reservoir lid 5116 compliantportion 5117 carrier 5118 reservoir inlet 5120 heater plate 5122reservoir outlet 5124 inlet tube 5125 inlet tube inner end 5126 outlettube 5127 outlet tube inner end 5128 inner end wall 5130 water reservoirdock 5132 first dock seal 5134 second dock seal 5136 turning vane 5138orifice 5139 sloped profile 5140 water filling indication mark 5140_awater filling indication mark 5140_b water filling indication mark5141_1 water level at predetermined maximum volume of water 5141_2 waterlevel at threshold volume of water 5142 retention protrusion 5144 docklocking recess 5146 base upper body 5148 base bottom plate 5150 sealingelement 5152 conductor plate 5154 handle recess 5156 handle recess 5158hinge 5159 hinge recess 5160 dock cavity 5166 handle grip 5168 dock airoutlet 5170 dock air inlet 5172 humidifier outlet 5174 base 5176 top5178 compliant portion 5180 cap 5182 water 5184 water level 5186reservoir latch 5192 baffle 5194 support spoke 5195 flow director 5196locating portion 5197 seal 5198 deflector portion 5200 thermal component5202 intermediate portion 5206 wall portion 5208 collapsible tube 5210flexible portion 5212 rigid portion 5220 rotation guide 5222 rotationstop 5224 inner lip 5226 outer lip 5240 heating element 5250 humidifiercontroller 5251 central humidifier controller 5252 heating elementcontroller 5254 heated air circuit controller 5300 humidifier end cap5310 end cap inlet 5320 end cap outlet 5330 end cap latch 5340 magnet5345 end cap magnet holder

1. A water reservoir for an apparatus for humidifying a flow of air,comprising: a base portion configured to hold a predetermined maximumvolume of water, the base portion including an overfill protectionelement configured and arranged to prevent filling the base portionabove the maximum volume of water.
 2. The water reservoir as claimed inclaim 1, further comprising a lid portion movably connected to the baseportion to allow the water reservoir to be convertible between an openconfiguration and a closed configuration.
 3. The water reservoir asclaimed in claim 2, wherein the overfill protection element isconfigured and arranged to prevent filling the base portion above themaximum volume of water when the water reservoir is in the openconfiguration and/or the closed configuration.
 4. The water reservoir asclaimed in claim 2, further comprising a compliant portion configured tosealingly engage the lid portion and the base portion when the reservoiris in the closed configuration.
 5. The water reservoir as claimed inclaim 4, wherein the compliant portion is configured to block or sealthe overfill protection element to prevent fluid communication into andout of the reservoir.
 6. The water reservoir as claimed in claim 1,wherein the overfill protection element is configured so that excesswater above the maximum volume of water will spill out via the overfillprotection element when the maximum volume of water is exceeded and thebase portion is in its normal, working orientation.
 7. The waterreservoir as claimed in claim 6, wherein the overfill protection elementcomprises at least one orifice that defines an egress path of water whenthe maximum volume of water is exceeded.
 8. The water reservoir asclaimed in claim 7, wherein the overfill protection element isconfigured such that water only spills out through the at least oneorifice when the maximum volume of water is exceeded.
 9. The waterreservoir as claimed in claim 7, wherein the at least one orifice isprovided in one or more positions along a perimeter of the base portion.10. The water reservoir as claimed in any one of claims 7-9, wherein theat least one orifice is provided through an upper lip or flange providedalong a perimeter of the base portion.
 11. The water reservoir asclaimed in claim 7, wherein the at least one orifice includes one ormore apertures, holes, slits, or slots that allows fluid communicationinto and out of the reservoir.
 12. The water reservoir as claimed inclaim 7, further comprising a compliant portion configured to sealinglyengage the base portion when the reservoir is in a closed configuration,wherein the compliant portion is configured to block or seal the atleast one orifice to prevent fluid communication into and out of thereservoir.
 13. The water reservoir as claimed in claim 12, wherein thecompliant portion sealing engages the base on an outside of the at leastone orifice.
 14. The water reservoir as claimed in claim 6, wherein theoverfill protection element comprises a sloped profile in a side profileof the base portion that defines an egress path of water when themaximum volume of water is exceeded.
 15. The water reservoir as claimedin claim 14, wherein the sloped profile extends in one or moredirections.
 16. The water reservoir as claimed in claim 14, wherein theoverfill protection element is configured such that water only spillsout through the sloped profile when the maximum volume of water isexceeded.
 17. The water reservoir as claimed in claim 14, furthercomprising a compliant portion configured to sealingly engage the baseportion when the reservoir is in a closed configuration, wherein thecompliant portion is configured to block or seal the sloped profile toprevent fluid communication into and out of the reservoir.
 18. The waterreservoir as claimed in claim 17, wherein the compliant portion sealingengages the base on an outer edge of the sloped profile.
 19. The waterreservoir as claimed in claim 3, wherein the overfill protection elementis configured and arranged to prevent filling the base portion above themaximum volume of water when the water reservoir is in the openconfiguration.
 20. The water reservoir as claimed in claim 3, whereinthe overfill protection element is configured and arranged to preventfilling the base portion above the maximum volume of water when thewater reservoir is in the closed configuration.
 21. The water reservoiras claimed in claim 1, wherein the overfill protection element forms oneor more air locks to prevent further ingress of water into the baseportion when the maximum volume of water is reached.
 22. The waterreservoir as claimed in claim 21, further comprising a lid portionmovably connected to the base portion to allow the water reservoir to beconvertible between an open configuration and a closed configuration.23. The water reservoir as claimed in claim 22, wherein the overfillprotection element is configured and arranged to form the one or moreair locks when the water reservoir is in the closed configuration. 24.The water reservoir as claimed in claim 21, further comprising an inlettube and an outlet tube in communication with the base portion, theinlet tube and the outlet tube being arranged such that, when themaximum volume of water is reached, air in the reservoir is preventedfrom escaping through the inlet tube and the outlet tube therebypreventing further ingress of water into the base portion.
 25. Anapparatus for humidifying a flow of air, comprising: a water reservoirdock; and the water reservoir according to claim 1 provided to the waterreservoir dock.
 26. The apparatus according to claim 25, wherein thewater reservoir dock forms a cavity to receive the water reservoir. 27.The apparatus according to claim 25, wherein the water reservoir dockincludes a heater plate adapted to thermally engage a conductive portionprovided to the water reservoir.
 28. A method of preventing overfillingin a humidifier reservoir, the method comprising: (i) incorporating anoverfill protection element in a base portion of the humidifierreservoir; and (ii) configuring the overfill protection element so thatexcess water above a predetermined maximum volume of water will spillout via the overfill protection element when the maximum volume of wateris exceeded and the base portion is in its normal, working orientation.29. The method as claimed in claim 28, wherein the overfill protectionelement includes at least one orifice.
 30. The method as claimed inclaim 28, wherein the overfill protection element includes a slopedprofile.
 31. The method as claimed in claim 28, further comprisingconfiguring the overfill protection element such that water only spillsvia the overfill protection element when the maximum volume of water isexceeded.